Weather DefinitionWeather is the day-to-day conditions of a particular place.For example: It was raining today at school. Yesterday it was sunny at home.

What is Climate?Climate is often spoken about at the same time as weather, but it is something quite different. The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years). We learn about different climates around the world. Deserts have a hot and dry climate while the Antarctic has a very cold and dry climate. 

Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy,

clear or cloudy.[1] Most weather phenomena occur in thetroposphere,[2][3] just below the stratosphere.

Weather generally refers to day-to-day temperature and precipitation activity, whereas climate is the term

for the average atmospheric conditions over longer periods of time.[4] When used without qualification,

"weather" is understood to be the weather of Earth.

Weather is driven by air pressure (temperature and moisture) differences between one place and another.

These pressure and temperature differences can occur due to the sun angle at any particular spot, which

varies by latitudefrom the tropics. The strong temperature contrast between polar and tropical air gives

rise to the jet stream. Weather systems in the mid-latitudes, such asextratropical cyclones, are caused by

instabilities of the jet stream flow. Because the Earth's axis is tilted relative to its orbital plane, sunlight is

incident at different angles at different times of the year. On Earth's surface, temperatures usually range

±40 °C (−40 °F to 100 °F) annually. Over thousands of years, changes in Earth's orbit affect the amount

and distribution of solar energy received by the Earth and influence long-term climate and global climate

change.

Forecasting

Forecast of surface pressures five days into the future for the north Pacific, North America, and north Atlantic ocean as on 9

June 2008

Weather forecasting is the application of science and technology to predict the state of theatmosphere for

a future time and a given location. Human beings have attempted to predict the weather informally for

millennia, and formally since at least the nineteenth century.[25][26]Weather forecasts are made by

collecting quantitative data about the current state of the atmosphere and using scientific understanding

of atmospheric processes to project how the atmosphere will evolve.[27]

Once an all-human endeavor based mainly upon changes in barometric pressure, current weather

conditions, and sky condition,[28][29] forecast models are now used to determine future conditions. Human

input is still required to pick the best possible forecast model to base the forecast upon, which involves

pattern recognition skills, teleconnections, knowledge of model performance, and knowledge of model

biases. The chaotic nature of the atmosphere, the massive computational power required to solve the

equations that describe the atmosphere, error involved in measuring the initial conditions, and an

incomplete understanding of atmospheric processes mean that forecasts become less accurate as the

difference in current time and the time for which the forecast is being made (the range of the forecast)

increases. The use of ensembles and model consensus helps to narrow the error and pick the most likely

outcome

Weather

Weather is the state of the atmosphere at a given time and place. Most weather takes place in thetroposphere, the lowest layer of the atmosphere.

Weather is measured and described in a variety of ways by meteorologists, scientists who study and predict weather. Air temperature and pressure, the amount and type of precipitation, the strength and direction of wind, and the types of clouds are all described in a weather report.

Weather changes each day because the air in our atmosphere is always moving, distributing energy from theSun. In most places in the world, the types of weather events also vary throughout the year as seasons change.

What is Weather?

Weather...

The term weather describes the state of the air at a particular place and time – whether it is warm or cold, wet or dry, and how cloudy or windy it is, for example.

Climate...

 

The normal pattern of weather experienced in a particular area over a long period of time is known as theclimate.   The climate tells us how hot, cold or wet it is likely to be in different parts of the world at different times of year. For example, tropical countries have hot climates and the Antarctic has a cold climate.

What is climate?Climate is the average weather usually taken over a 30-year time period for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for

a particular region. Weather describes the short-term state of the atmosphere. 

What is our climate system?

Atmosphere

The atmosphere covers the Earth. It is a thin layer of mixed gases which make up the air we breathe. This thin layer also helps the Earth from becoming too hot or too cold.

OceansOceans cover about 70 percent of Earth's surface. Their large size and thermal properties allow them to store a lot of heat.

Land Land covers 27 percent of Earth's surface and land topography influences weather patterns.

Ice

Ice is the world's largest supply of freshwater. It covers the remaining 3 percent of Earth's surface including most of Antarctica and Greenland. Ice plays an important role in regulating climate, because it is highly reflective.

Biosphere

The biosphere is the part of Earth's atmosphere, land, and oceans that supports any living plant, animal, or organism. It is the place where plants and animals, including humans, live.

What is weather? The weather is just the state of the atmosphere at any time, including things such as temperature, precipitation, air pressure and cloud cover. Daily changes in the weather are due to winds and storms. Seasonal changes are due to the Earth revolving around the sun.

 

What causes weather? Because the Earth is round and not flat, the Sun's rays don't fall evenly on the land and oceans. The Sun shines more directly near the equator bringing these areas more warmth. However, the polar regions are at such an angle to the Sun that they get little or no

sunlight during the winter, causing colder temperatures. These differences in temperature create a restless movement of air and water in great swirling currents to distribute heat energy from the Sun across the planet. When air in one region is warmer than the surrounding air, it becomes less dense and begins to rise, drawing more air in underneath. Elsewhere, cooler denser air sinks, pushing air outward to flow along the surface and complete the cycle.

Why do mountains affect weather and climate?There are two sides to a mountain: wayward and leeward. Whenever it is raining, the wayward side gets the rain. As a cloud goes up the mountain, it keeps raining until there is no more water in the cloud. Now, as the cloud starts to go down the other side of the mountain, there is no more precipitation. So, the leeward side of the mountain doesn't get any rain. The flat ground on this side of the mountain is dry and humid. 

What is the Water Cycle?Earth has a limited amount of water. So, that water keeps going around. We call it the water cycle. The water cycle begins with evaporation. Evaporation is when the sun heats up water in rivers, lakes or the ocean. Then turns it into water vapor or steam. The water vapor or steam leaves the body of water and goes into the air. Transpiration is the process by which plants lose water out of their leaves. Condensation is when water vapor in the air gets cold and changes back into water to form clouds. Think of it this way, when you open a cold soda on a hot summer day, your soda will start to sweat as water droplets form on the outside of the can. Precipitation occurs when so much water has condensed that the air can't hold it anymore. This is how we get rain or snow. Collection happens when the precipitation falls and is collected back in the oceans, lakes and rivers. When it falls to the ground, it will soak into the earth and become ground water. This is the water cycle and it just keeps repeating.

Click Here to learn more about the Earth's water cycle.

Why do we have seasons?As the Earth spins on its axis, producing night and day, it also moves about the Sun in an elliptical (elongated circle) orbit that requires 365 1/4 days to complete. The Earth's axis is tilted at 23.5 degrees and is why we have seasons. When the Earth's axis points towards the Sun, it is summer for that hemisphere. When the Earth's axis points away, winter can be expected.

What is the significance of the Sun to the Earth?Without the Sun, there would be no weather. Earth is positioned as the third planet, so our temperatures are sustainable for life. The average temperature of Mars is much colder, while Venus is much hotter. 

ClimateFrom Wikipedia, the free encyclopedia

For other uses, see Climate (disambiguation).

Worldwide Climate Classifications

Climate encompasses the statistics oftemperature, humidity, atmospheric pressure,wind, precipitation,

atmospheric particle count and other meteorological elemental measurements in a given region over long

periods. Climate can be contrasted to weather, which is the present condition of these elements and their

variations over shorter periods.

A region's climate is generated by the climate system, which has five

components:atmosphere, hydrosphere, cryosphere, land surface, and biosphere.[1]

The climate of a location is affected by itslatitude, terrain, and altitude, as well as nearbywater bodies and their

currents. Climates can beclassified according to the average and the typical ranges of different variables, most

commonly temperature and precipitation. The most commonly used classification scheme was originally

developed by Wladimir Köppen. The Thornthwaite system,[2] in use since 1948,

incorporates evapotranspiration along with temperature and precipitation information and is used in studying

animal species diversity and potential effects of climate changes. The Bergeron and Spatial Synoptic

Classification systems focus on the origin of air masses that define the climate of a region.

Paleoclimatology is the study of ancient climates. Since direct observations of climate are not available before

the 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such as

sediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climate

models are mathematical models of past, present and future climates. Climate change may occur over long

and short timescales from a variety of factors; recent warming is discussed in global warming.

Why do the seasons change?Answer:

Seasons change because the axis of the earth is tilted by 23.5 degrees (from a line

perpendicular to its orbit). As the earth moves around its orbit there is a time when it

is tilted towards the sun and so receives a higher concentration of the sun's energy

(summer) and a time when it is tilted away and receiving less energy (winter). This

also explains why it is summer in N hemisphere when it is winter in S hemisphere.

What are the five different world climate zones?Answer:In the Koppen system:

A - Tropical Moist Climates: all months have average temperatures above 18° Celsius.

B - Dry Climates: with deficient precipitation during most of the year.

C - Moist Mid-latitude Climates with Mild Winters.

D - Moist Mid-Latitude Climates with Cold Winters.

E - Polar Climates: with extremely cold winters and summers.

Temperature is a physical quantity that indicates degrees of hot and cold on a numerical scale.[1] It refers to states of matter or radiation in a local region. It is measured by a thermometer, which may be calibrated to a variety oftemperature scales.

What is Temperature?

In a qualitative manner, we can describe the temperature of an object as that which determines the sensation of warmth or coldness felt from contact with it.

It is easy to demonstrate that when two objectsof the same material are placed together (physicists say when they are put in thermal contact), the object with the higher temperature cools while the cooler object becomes warmer until a point is reached after which no more change occurs, and to our senses, they feel the same. When the thermal changes have stopped, we say that the two objects (physicists define them more rigorously as systems) are in thermal equilibrium . We can then define the temperature of the system by saying that the temperature is that quantity which is the same for both systems when they are in thermal equilibrium.

If we experiment further with more than two systems, we find that many systems can be brought into thermal equilibrium with each other; thermal equilibrium does not depend on the kind of object used. Put more precisely,

if two systems are separately in thermal equilibrium with a third, then they must also be in thermal equilibrium with each other,

and they all have the same temperature regardless of the kind of systems they are.

The statement in italics, called the zeroth law of thermodynamics may be restated as follows:

If three or more systems are in thermal contact with each other and all in equilibrium together, then any two taken separately are in equilibrium with one another. (quote from T. J. Quinn's monograph Temperature)

Now one of the three systems could be an instrument calibrated to measure the temperature - i.e. a thermometer. When a calibrated thermometer is put in thermal contact with a system and reaches thermal equilibrium, we then have a quantitative measure of the temperature of the system. For example, a mercury-in-glass clinical thermometer is put under the tongue of a patient and allowed to reach thermal equilibrium in the patient's mouth - we then see by how much the silvery mercury has expanded in the stem and read the scale of the thermometer to find the patient's temperature.

Temperature

A convenient operational definition of temperature is that it is a measure of the average translational kinetic energy associated with the disordered microscopic motion of atoms and molecules. The flow of heat is from a high temperature region toward a lower temperature region. The details of the relationship to molecular motion are described in kinetic theory.The temperature defined from kinetic theory is called the kinetic temperature. Temperature is not directly proportional to internal energy since temperature measures only the kinetic energy part of the internal energy, so two objects with the same temperature do not in general have the same internal energy (see water-metal example). Temperatures are measured in one of the three standard temperature scales (Celsius, Kelvin, and Fahrenheit).

HumidityTropical forests often have high humidity.

Humidity is the amount of water vapor in the air. Water vapor is the gas phase of water and is invisible.

[1] Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness

of sweating in cooling the body by reducing the rate of evaporationof moisture from the skin. This effect is

calculated in a heat index table, used during summer weather.

There are three main measurements of humidity: absolute, relative and specific. Absolute humidity is the

water content of air.[2] Relative humidity, expressed as a percent, measures the current absolute

humidity relative to the maximum for that air pressure and temperature. Specific humidity is a ratio of the

water vapor content of the mixture to the total air content on a mass basis

Types

[edit]Absolute humidity

Absolute humidity is an amount of water vapor, usually discussed per unit volume. The mass of water

vapor,  , per unit volume of total air and water vapor mixture,  , can be expressed as follows:

Absolute humidity in air ranges from zero to roughly 30 grams per cubic meter when the air is

saturated at 30 °C.[3] (See alsoClimate/Humidity table)

The absolute humidity changes as air temperature or pressure changes. This is very inconvenient

for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary

considerably. As a result, absolute humidity is generally defined in chemical engineering as mass of

water vapor per unit mass of dry air, also known as the mass mixing ratio (see below), which is

much more rigorous for heat and mass balance calculations. Mass of water per unit volume as in the

equation above would then be defined asvolumetric humidity. Because of the potential

confusion, British Standard BS 1339 (revised 2002) suggests avoiding the term "absolute humidity".

Units should always be carefully checked. Most humidity charts are given in g/kg or kg/kg, but any

mass units may be used.

The field concerned with the study of physical and thermodynamic properties of gas-vapor mixtures is

named Psychrometrics.

Relative humidity

Relative humidity is the ratio of the partial pressure of water vapor in the air-water mixture to

the saturated vapor pressure of water at those conditions. The relative humidity of air is a function of

both its water content and temperature.

Relative humidity is normally expressed as a percentage and is calculated by using the following

equation. It is defined as the ratio of the partial pressure of water vapor (H2O)   in the mixture to

the saturated vapor pressure of water   at a prescribed temperature.

[3]

Relative humidity is an important metric used in weather forecasts and reports, as it is an

indicator of the likelihood of precipitation, dew, or fog. In hot summer weather, a rise in

relative humidity increases the apparent temperature to humans (and other animals) by

hindering the evaporation of perspiration from the skin. For example, according to the Heat

Index, a relative humidity of 75% at 80°F (27°C) would feel like 83.574°F ±1.3 °F (28.652°C

±0.7 °C) at ~44% relative humidity.[4][5]

[edit]Specific humidity

Specific humidity is the ratio of water vapor to dry air in a particular mass, and is sometimes

referred to as humidity ratio. Specific humidity ratio is expressed as a ratio of mass of water

vapor,  , per unit mass of dry air   [6] . This is in conflict with the ASHRAE 2009

Handbook, Ch1,1.2, (9a) which defines Specific humidity as "the ratio of the mass of water

vapor to total mass of the moist air sample".

That ratio is defined as:

Specific humidity can be expressed in other ways including:

or:

Using the definition of specific humidity, the relative humidity can be expressed

as

However, specific humidity is also defined as the ratio of water vapor to the

total mass of the system in meteorology.[7] "Mixing ratio" is used to name

the definition in this section beginning.[8]

[edit]Measurement

hygrometer

There are various devices used to measure and regulate humidity. A

device used to measure humidity is called a psychrometer or hygrometer.

A humidistat is a humidity-triggered switch, often used to control

a dehumidifier.

Humidity is also measured on a global scale using remotely

placed satellites. These satellites are able to detect the concentration of

water in the troposphere at altitudes between 4 and 12 kilometers.

Satellites that can measure water vapor have sensors that are sensitive

to infrared radiation. Water vapor specifically absorbs and re-radiates

radiation in this spectral band. Satellite water vapor imagery plays an

important role in monitoring climate conditions (like the formation of

thunderstorms) and in the development of futureweather forecasts.

Atmospheric pressureFrom Wikipedia, the free encyclopedia

"Air pressure" redirects here. For the pressure of air in other systems, see pressure.

Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above that surface

in the atmosphere of Earth (or that of another planet). In most circumstances atmospheric pressure is closely

approximated by the hydrostatic pressurecaused by the mass of air above the measurement point. Low-

pressure areas have less atmospheric mass above their location, whereas high-pressure areas have more

atmospheric mass above their location. Likewise, as elevation increases, there is less overlying atmospheric

mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one

square centimeter in cross-section, measured from sea level to the top of the atmosphere, has a mass of about

1.03 kg and weight of about 10.1 N (2.28 lbf) (A column one square inch in cross-section would have a weight

of about 14.7 lbs, or about 65.4 N). Over the area of your body, there is about 1,000 kg of air; this is

approximately the same as having a small car press down on you

What Is Atmospheric PressureJust answering the question ‘what is atmospheric pressure?’ is not enough to give a full understanding of its importance. By definition atmospheric pressure is ‘force per unit area exerted against a surface by the weight of air above that surface’. Atmospheric pressure is closely related to the hydrostatic pressure caused by the weight of air above the measurement point. The term standard atmosphere is used to express the pressure in a system(hydraulics and pneumatics) and is equal to 101.325 kPa. Other equivalent units are 760 mmHg and 1013.25 millibars.

Mean sea level pressure (MSLP) is the pressure at sea level. This is the pressure normally given in weather reports. When home barometers are set to match local weather reports, they will measure pressure reduced to sea level, not your local atmospheric pressure. The reduction to sea level means that the normal range of fluctuations in pressure are the same for everyone.Atmospheric pressure is important in altimeter settings for flight. A altimeter can be set for QNH or QFE. Both are a method of reducing atmospheric pressure to sea level, but they differ slightly. QNH will get the altimeter to show elevation at the airfield and altitude above the air field. QFE will set the altimeter to read zero for reference when at a particular airfield. QNH is transmitted around the world in millibars, except in the United States and Canada . These two countries use inches (or hundredths of an inch) of mercury.Atmospheric pressure is often measured with a mercury barometer; however, since mercury is not a substance that humans commonly come in contact with, water often provides a more intuitive way to visualize the pressure of one atmosphere. One atmosphere is the amount of pressure that can lift water approximately 10.3m. A diver who is 10.3m underwater experiences a pressure of about 2 atmospheres (1of air plus 1of water). Low pressures like natural gas lines can be expressed in inches of water(w.c). A typical home gas appliance is rated for a maximum of 14 w.c.(about 0.034 atmosphere).You can see that understanding ‘what is atmospheric pressure’ is just the tip of the iceberg. Once you have the definition in mind, it really comes together when you see the wide variety of applications.

Differences between air and wind?

Air is the mixture of gases that forms the atmosphere, which we have all around us.

When this air begin to move fast enough to matter, we call it wind.

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sunthrough space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space.

Winds are commonly classified by their spatial scale, theirspeed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in our solar system occur on Neptune and Saturn.

What is Air Pressure?

Imagine a group of acrobats at the circus. One climbs up and stands on another's shoulders. The weight of the acrobat on top puts more pressure on the one below. Then another acrobat climbs up and stands on the second acrobat's shoulders. Now there's even more pressure on the acrobat on the bottom because he is under the weight of the two acrobats above him. It's the same with air. Yes, air has weight, and probably more than you think. In fact, the weight of the air on your desk at school weighs about 11,000 pounds. That's about the same weight as a school bus! Since air pressure pushes in all directions, the air pressure pushing up from under your desk balances out the air pushing down on it, so the desk doesn't collapse under the weight. Just like an acrobat with two people stacked on his shoulders would want to move to where there wasn't so much pressure on him, air moves from areas where the pressure is higher to where it is lower

The density of air,

The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronauticsand other sciences. Air density decreases with increasing altitude, as does air pressure. It also changes with variances in temperature or humidity. At sea level and at 15 °C according to ISA (International Standard Atmosphere), air has a density of approximately 1.225

kg/m3 (0.0023769 slugs/ft3).

Rain

Torrential rain in Greece.

Rain is liquid water in the form of droplets that have condensed fromatmospheric water vapor and

then precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the water

cycleand is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for

many types of ecosystem, as well as water for hydroelectric power plants and crop irrigation.

The major cause of rain production is moisture moving along three-dimensional zones of temperature and

moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation

falls from convective clouds (those with strong upward vertical motion) such ascumulonimbus (thunder clouds)

which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope

flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall

out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to

the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of

the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.

rain·fall 1. A shower or fall of rain.2. The quantity of water, expressed in inches, precipitated as rain, snow, hail, or sleet in a specified area and time interval.

Rainfall

Rainfall in Ireland

Most of the eastern half of the country gets between 750 and 1000 (mm) of rainfall in the year. Rainfall in the west generally averages between 1000 and 1400 mm. In many mountainous districts rainfall exceeds 2000mm per year. The wettest months, in almost all areas are December and January. April is the driest month generally across the country. However, in many southern parts, June is the driest. Hail and snow contribute relatively little to the precipitation measured.

How Often Does it Rain?

The general impression is that it rains quite a lot of the time in Ireland, but two out of three hourly observations will not report any measurable rainfall. The average number of wet days (days 1mm or more of rain) ranges from about 150 days a year along the east and south east coasts, to about 225 days a year in parts of the west.

How Heavy is the Rain?

Unlike the rain in many other countries, especially in the tropics, average hourly rainfall amounts in Ireland are quite low, ranging from 1 to 2mm. Short-term rates can of course be much higher: for example, an hourly total of 10mm is not uncommon and totals of 15 to 20mm in an hour may be expected to occur once in 5 years. Hourly totals exceeding 25mm are rare in this country and when they do occur they are usually associated with heavy thunderstorms.

Information on the frequency of heavy rainfalls is often required by engineers, architects and others, usually in connection with design criteria for water management or drainage schemes. A depth duration frequency model allows for the estimation of point rainfall frequencies for a range of durations for any location in Ireland. For more information, seewww.met.ie/climate/products03.asp .

An atmosphere (New Latin atmosphaera, created in the 17th century from Greek ἀτμός [atmos]

"vapor"[1] and σφαῖρα [sphaira] "sphere"[2]) is a layer of gases that may surround a material body of

sufficient mass,[3] and that is held in place by the gravity of the body. An atmosphere may be retained for

a longer duration, if the gravity is high and the atmosphere's temperature is low. Some planets consist

mainly of various gases, but only their outer layer is their atmosphere.

The term stellar atmosphere describes the outer region of a star, and typically includes the portion starting

from the opaque photosphere outwards. Relatively low-temperature stars may form compound molecules

in their outer atmosphere. Earth's atmosphere, which containsoxygen used by

most organisms for respiration and carbon dioxide used

by plants, algaeand cyanobacteria for photosynthesis, also protects living organisms from genetic

damage by solar ultraviolet radiation. Its current composition is the product of billions of years of

biochemical modification of the paleoatmosphere by living organisms.

The present atmosphere of the Earth is probably not its original atmosphere. Our current atmosphere is what chemists would call an oxidizing atmosphere, while the original atmosphere was what chemists would call a reducing atmosphere. In particular, it probably did not contain oxygen.

Composition of the Atmosphere

The original atmosphere may have been similar to the composition of the solar nebula and close to the present composition of the Gas Giant planets, though this depends on the details of how the planets condensed from the solar nebula. That atmosphere was lost to space, and replaced by compounds outgassed from the crust or (in some more recent theories) much of the atmosphere may have come instead from the impacts of cometsand other planetesimals rich in volatile materials.

The oxygen so characteristic of our atmosphere was almost all produced by plants (cyanobacteria or, more colloquially, blue-green algae). Thus, the present composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% other gases.

Layers of the Atmosphere

The atmosphere of the Earth may be divided into several distinct layers, as the following figure indicates.

Layers of the Earth's atmosphere

Earth's Atmosphere

The atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surrounds Earth. High above the planet, the atmosphere becomes thinner until it gradually reaches space. It is divided into five layers. Most of the weather and clouds are found in the first layer.

The atmosphere is an important part of what makes Earth livable. It blocks some of the Sun's dangerous rays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen within our atmosphere is essential for life.

cryosphere 

The cryosphere (from the Greek κρύος cryos "cold", "frost" or "ice" andσφαῖρα sphaira, "globe, ball"[1]) is the term which collectively describes the portions of the Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost). Thus there is a wide overlap with thehydrosphere. The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in global climate and in climate modelresponse to global change.

biosphere

The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a

closed (apart from solar and cosmic radiation), and self-regulating system.[1] From the

broadestbiophysiological point of view, the biosphere is the global ecologicalsystem integrating all living

beings and their relationships, including their interaction with the elements of

the lithosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning

through a process of biogenesis or biopoesis, at least some 3.5 billion years ago.[2]

In a broader sense; biospheres are any closed, self-regulating systems containing ecosystems; including

artificial ones such asBiosphere 2 and BIOS-3; and, potentially, ones on other planets or moons. but they

can be open systems too. [3]

lithosphere 

The lithosphere (Ancient Greek: λίθος [lithos] for "rocky", andσφαῖρα [sphaira] for "sphere") is the

rigid[1] outermost shell of a rockyplanet. On Earth, it comprises the crust and the portion of the uppermantle that behaves elastically on time scales of thousands of years or greater.

In the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard and

rigid outer layer of the Earth. The lithosphere is underlain by the asthenosphere, the weaker, hotter, and

deeper part of the upper mantle. The boundary between the lithosphere and the underlying

asthenosphere is defined by a difference in response to stress: the lithosphere remains rigid for very long

periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere

deforms viscously and accommodates strain through plastic deformation. The lithosphere is broken

into tectonic plates. The uppermost part of the lithosphere that chemically reacts to

the atmosphere, hydrosphere and biospherethrough the soil forming process is called the pedosphere.

The concept of the lithosphere as Earth’s strong outer layer was developed by Joseph Barrell, who wrote

a series of papers introducing the concept.[2][3][4][5] The concept was based on the presence of significant

gravity anomalies over continental crust, from which he inferred that there must exist a strong upper layer

(which he called the lithosphere) above a weaker layer which could flow (which he called the

asthenosphere). These ideas were expanded by Harvard geologist Reginald Aldworth Daly in 1940 with

his seminal work "Strength and Structure of the Earth"[6] and have been broadly accepted by geologists

and geophysicists. Although these ideas about lithosphere and asthenosphere were developed long

before plate tectonic theory was articulated in the 1960s, the concepts that a strong lithosphere exists and

that this rests on a weak asthenosphere are essential to that theory.

There are two types of lithosphere:

Oceanic lithosphere, which is associated with Oceanic crust and exists in the ocean basins

Continental lithosphere, which is associated with Continental crust

The hydrosphere (from Greek ὕδωρ - hudōr, "water"[1] and σφαῖρα - sphaira, "sphere"[2]) in physical

geography describes the combined mass of water found on, under, and over the surface of a planet.

The total mass of the Earth's hydrosphere is about 1.4 × 1018 tonnes, which is about 0.023% of the

Earth's total mass. About 20 × 1012 tonnes of this is in the Earth's atmosphere (the volume of one tonne of

water is approximately 1 cubic metre). Approximately 75% of the Earth's surface, an area of some 361

million square kilometers (139.5 million square miles), is covered by ocean. The averagesalinity of the

Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5%) [3]

The hydrosphere is the liquid water component of the Earth. It includes the oceans, seas, lakes, ponds, rivers and streams. The hydrosphere covers about 70% of the surface of the Earth and is the home for many plants and animals.

(U.S. Fish and Wildlife Service/Craig Blacklock)

The hydrosphere, like the atmosphere, is always in motion. The motion of rivers and streams can be easily seen, while the motion of the water within lakes and ponds is less obvious. Some of the motion of the oceans and seas can be easily seen while the large scale motions that move water great distances such as between the tropics and poles or between continents are more difficult to see. These types of motions are in the form of currents that move the warm waters in the tropics toward the poles, and colder water from the polar regions toward the tropics. These currents exist on the surface of the ocean and at great depths in the ocean (up to about 4km).

(NOAA Photo Collection/Commander John Bortniak, NOAA Corps)Large version

The characteristics of the ocean which affects its motion are its temperature and salinity. Warm water is less dense or lighter and therefore tends to move up toward the surface, while colder water is more dense or heavier and therefore tends to sink toward the bottom. Salty water is also more dense or heavier and thus tends to sink, while fresh or less salty water is less dense or lighter and thus tends to rise toward the surface. The combination of the water's temperature and salinity determines whether it rises to the surface, sinks to the bottom or stays at some intermediate depth.

ES0108  Hydrosphere/Atmosphere Interactions

Layers of the Atmosphere:

The earth is surrounded by the atmosphere, which is the body of air or gasses that protects the planet

and enables life. Most of our atmosphere is located close to the earth's surface where it is most dense.

The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is

composed of carbon dioxide and other gasses. There are five distinct layers of the earth. Let's look at

each, from closest to farthest from the earth...

Troposphere:

The layer of the atmosphere closest to the earth is the troposphere. This layer is where weather

occurs. It begins at the surface of the earth and extends out to about 4-12 miles. The temperature of

the troposphere decreases with height. This layer is known as the lower atmosphere.

Stratosphere:

Above the troposphere is the stratosphere, which extends to about 30-35 miles above the earth's

surface. Temperature rises within the stratosphere but still remains well below freezing.

Mesosphere:

From about 35 to 50 miles above the surface of the earth lies the mesosphere, where the air is

especially thin and molecules are great distances apart. Temperatures in the mesosphere reach a low

of -184°F (-120°C). The stratosphere and the mesosphere are the middle atmosphere.

Thermosphere:

The thermosphere rises several hundred miles above the earth's surface, from 50 miles up to about

400 miles. Temperature increases with height and can rise to as high as 3,600°F (2000°C).

Nonetheless, the air would feel cold because the hot molecules are so far apart. This layer is known as

the upper atmosphere.

Exosphere:

Extending from the top of the thermosphere to 6200 miles (10,000 km) above the earth is the

exosphere. This layer has very few atmospheric molecules, which can escape into space.

Pauses...:

Between each layer of the atmosphere is a boundary. Above the troposphere is the tropopause; above

the stratosphere is the stratopause; above the mesosphere is the mesopause; and above the

thermosphere is the thermopause. At these "pauses," maximum change between the "spheres" occur.

The Layered Atmosphere

Stand outside and look up. What do you see? You might see blue sky or wooly clouds. At night you might see stars, a satellite or a crescent moon. What you are not seeing, however, is the complexity of our atmosphere. The atmosphere is a protective layer of gasses that shelters all life on Earth, keeping temperatures within a relatively small range and blocking out harmful rays of sunlight.

The atmosphere has five different layers that are determined by the changes in temperature that happen with increasing altitude.

TroposphereLiving at the surface of the Earth, we are usually only aware of the events happening in the lowest layer, the troposphere, where all weather occurs. The base of this layer is warmer than its top because the air is heated by the surface of the Earth, which absorbs the Sun’s energy.

StratosphereAbove the troposphere lies the stratosphere where jet airplanes fly. Temperatures increase with altitude because of increasing amounts of ozone. The ozone layer within the stratosphere absorbs harmful ultraviolet rays of sunlight.

MesosphereAs the mesosphere extends upward above the stratosphere, temperatures decrease. The coldest parts of our atmosphere are located in this layer and can reach –90°C.

ThermosphereIn the forth layer from Earth’s surface, the thermosphere, the air is thin, meaning that there are far fewer air molecules. The thermosphere is very sensitive to solar activity and can heat up to 1,500°C or higher when the Sun is active making an aurora that lights up the night sky. Astronauts orbiting Earth in the space station or space shuttle spend their time in this layer.

ExosphereThe upper layer of our atmosphere, where atoms and molecules escape into space, is called the exosphere. 

Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above that surface in the atmosphere of Earth (or that of another planet). In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressurecaused by the mass of air above the measurement point. Low-pressure areas have less atmospheric mass above their location, whereas high-pressure areas have more atmospheric mass above their location. Likewise, as elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one square centimeter in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kg and weight of about 10.1 N (2.28 lbf) (A column one square inch in cross-section would have a weight of about 14.7 lbs, or about 65.4 N). Over the area of your body, there is about 1,000 kg of air; this is approximately the same as having a small car press down

on you.[1]

Pressure

Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior. The standard unit for pressure is the Pascal, which is a Newton per square meter.

For an object sitting on a surface, the force pressing on the surface is the weight of the object, but in different orientations it might have a different area in contact with the surface and therefore exert a different pressure.

Wind speed, or wind velocity, is a fundamental atmospheric rate.

Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth

and metabolism rate of many plant species, and countless other implications.[1]

Wind speed is now commonly measured with an anemometer but can also be classified using the

older Beaufort scale which is based on people's observation of specifically defined wind effects.

Climate variation factors 

The climate of any region is largely determined by four geographic aspects:

Latitude, distance from the sea, direction of the prevailing winds and elevation.

 Climate variation factors

Other factors influence the global climate system: atmosphere, oceans, ice, land and the various forms of life.

Ultraviolet, visible and infra-red solar radiations are Earth's main sources of energy. There is an established balance between the incmoing solar energy and the telluric infra-red radiation emitted by the Earth. Part of the Earth's radiation is absorbed and reemitted by the 'greenhouse' effect and part is lost in space. You'd be hard pressed to find people anywhere that don't have an opinion on the 'greenhouse' effect or solar radiations one way or the other.

 Horizontal variation of solar energy

The balance is fragile and any variation in the factors that affect this incoming and outgoing energy process or which modifies the energy repartition will affect the world climate.

Natural factors

The climate changed during Earth's history. Ice ages alternating with warm periods provide an example. Some changes were worlwide, while others simply affected an area or a hemisphere. In addition, a number of natural factors contribute to modify the Earth's climate during various periods. It is important to understand these factors when seeking to detect the influence of humanity on the climate:

Variations of the solar energy emissions. The quantity of energy emitted by the Sun is not constant. There are evidences revealing that the Earth's temperature corresponds to a solar cycle. Long term changes can occur.

Modifications of the Earth's orbit. The orbit of the Earth around the Sun changes slowly. This influences the quantity of energy which is reflected and absorbed. It is thought that these variations of Earth's orbit are one of the factors that triggered the ice ages.

 Seasonal variations of the air temperature

The greenhouse effect. Approximately 1/3 of the energy emitted by the Sun returns to space after penetrating Earth's atmosphere. A fraction of what remains is then absorbed by the atmosphere, but the major part is absorbed by the Earth's surface. The surface returns infra-red energy and while part of this energy is lost in space, another part is absorbed again and re-emitted by the clouds and gases like water vapor, carbon dioxide, methane and oxide nitrous. This contributes to heat Earth's surface and the troposphere to a temperature 33°C higher than what it would be otherwise.It is the natural greenhouse effect which is essential for life.

Aerosols. These are very fine particles that remain in suspension in the atmosphere during a very long time. They reflect the solar radiation and also absorb it. By modifying the quantity of the aerosols in the atmosphere, one modifies the quantity of the reflected and absorbed solar energy.

Human factors

The greenhouse effect amplification. The greenhouse gases naturally present in the atmosphere (e.g., water vapor, carbon dioxide, methane and oxide nitrous) keep the Earth at a sufficiently high temperature so that life is possible. Scientific studies reveal that various human activities, whose combustion of fossile fuels for producing electrical energy, heating and transport, produce greenhouse gases. By increasing concentrations of these gases and by rejecting new greehouse gases such as chloroflurocarbures (CFC), humans are likely to be contributing to increasing the average temperatures of Earth.

Lan use evolution. By replacing forests with arable lands or the natural vegetation by asphalt and concrete, humanity modifies the way in which terrestrial surface reflects sunlight and releases heat. All

these changes can also modify the regional configurations of evaporation, streaming and rains.

Atmospheric aerosols. Due to its agricultural and industrial activities, humanity adds great quantities of fine particles called aerosols to the atmosphere. Most of the aerosols are quickly falling due to gravity and precipitations, but they do not less influence the atmosphere radiative absorption. It is the quantity and the nature of these particles as well as the nature of underneeth surface (land or water) that determine if this have a heating effect of not. Nevertheless, the regional effects can be important.

Types of Climate VariationClimate, although very slowly, keeps evolving. There are many causes behind variation in climate.

Climate variations can be categorized into two broad contexts.

Natural Climate Variation: There are several natural causes that force climate to change across time and scale. It

can be further drilled down into the following categories.o Natural Forcings of the Climate System

Natural Forcings of the Climate SystemNatural forcings are of two types.  

External Forcings: These are essentially linked to changes in the orbital parameters of the earth that control the intensity and location of incident solar radiation, and fluctuations in solar energy. 

Internal Forcings: These comprise all those changes that occur within the earth system itself, in particular volcanic activity, fluctuations in ocean circulations and large-scale changes in the marine and terrestrial biosphere or in the cryosphere.

The Sun and the Global Energy BalanceThe Sun is the prime source of external energy for the earth. Every moment, huge amount of energy reaches the

earth from the Sun. Let us see this animation that shows what happens to the solar radiation that reaches the earth.

Of the energy that remains in the earth (absorbed by atmosphere, clouds, and earth’s surface)

64% is radiated out into the space (atmosphere and clouds)

6% is radiated directly into the space by earth’s surface

7% is utilized in the movement of air

23% is utilized in evaporation of water from earth’s surface

This is how the balance of energy is maintained in the environment. The global energy balance is, therefore, the

balance between incoming energy from the Sun and outgoing heat from the earth.

From the animation, we find that of the total energy that reaches the earth6% is reflected by atmosphere

16% is absorbed by atmosphere

20% is reflected by clouds

3% is absorbed by clouds

51% is absorbed by oceans and land

4% is reflected by the surface of the earth

Greenhouse EffectGreenhouse effect is a phenomenon whereby earth’s atmosphere traps solar radiation, caused by the presence

of gases such as carbon dioxide, water vapour, and methane that allow incoming sunlight to pass through but absorb

the heat radiated back from earth’s surface. The gases that trap heat radiated from the earth are called

greenhouse gases (GHGs).

Let us see what exactly this mechanism is.

Except for GHGs, other gases have no extra capacity to absorb heat. Hence, GHGs are the main contributors in

trapping heat in the atmosphere.

GHG and non-GHG components in air:

Greenhouse effect is essential for our survival – without greenhouse effect, the earth would become too cold to live.

The increasing greenhouse effect is the prime concern for our survival – being too hot is not pleasing either

Greenhouse Gases Non-Greenhouse GasesWater vapour, H2O Carbon dioxide, CO2

Methane, CH4

Nitric oxide, NO2

Ozone, O3

HydrocarbonsChlorofluorocarbons

Nitrogen, N2

Oxygen, O2

Argon, ArCarbon monoxide, COSulphur dioxide, SO2

Internal and external forcings, global energy balance, radiative forcing and greenhouse effect together constitute the

natural forcings of the climate. These are the natural causes that forces climate to change.

Now let us study about the natural climate variability.

o Natural Variability of the Climate

Natural Variability of the ClimateNatural climate variability, as the name suggests, is caused by natural factors. 

There are lots of natural factors that cause significant changes in the climate. These causes can

be within the earth or coming from outside the earth. Based on this, the natural climate

variability can be categorized into two groups.

Externally Induced Climate Variability: It refers

to the impact of some external factor that leads to

variability, such as the impact of

Variations in solar radiation

Solar and lunar tides

Internally Induced Climate Variability: It refers to

internal interactions between components of the

climate system, such as the interaction between

Ocean and atmosphere

Atmosphere and biosphere

Externally and Internally Induced Climate Variability

Feedback

FeedbackFeedback is the response of the climate to the internal variability of the climate system and to external forcings.

Interestingly, the response of climate against a change can induce or reduce further change. Based on this, feedback can be classified into 

Positive Feedback: A positive feedback cycle is a cycle where the effect reinforces the cause. This means that the impact will go on increasing. Let us understand the example shown in the screen.

When the surface temperature increases, it leads to increased evaporation from the ocean. This adds more water vapour to the atmosphere. Water vapour, being a GHG, further increases the surface temperature.

Thus, we find that an increase in surface temperature assists a further increase in the surface temperature. This is an instance of positive feedback.

Negative Feedback: A negative feedback cycle is a cycle where the effect resists the cause. This means that the impact will go on diminishing. Let us understand the example shown in the screen.

When surface temperature increases, it leads to a higher evaporation rate. More water vapour in the atmosphere means more cloud formation. More clouds lead to increased albedo of the earth. This decreases the surface temperature slightly. This leads to decreased evaporation from oceans. This leads to lesser clouds and lowering of earth’s albedo. This leads to decrease in surface temperature.

Thus, we find that an increase in surface temperature resists further increase in surface temperature. This is an instance of negative feedback.

Global and Hemispherical Variability

Global and Hemispherical VariabilityClimate varies naturally on all time-scales. In the last few million years, the glacial periods and

the inter-glacial periods have alternated as a result of variations in earth’s orbit. 

However, recently it was discovered that in the last glacial period large and very rapid

temperature variations took place over large parts of the globe, in particular in the higher

latitudes of the Northern Hemisphere. These led to an increase in temperature over these

regions by a few degrees. In contrast, the last 10,000 years appear to have been relatively

more stable, though locally quite large changes have occurred. 

Recent analyses suggest that in the Northern Hemisphere climate of the past 1,000 years was

characterized by an irregular but steady cooling, followed by a strong warming during the 20th

century. 

For the Southern Hemisphere, the data is not as precise, but it does indicate that temperature

changes in past centuries were markedly different from those in the Northern Hemisphere; the

only obvious similarity being the strong warming during the 20th century.

Over and above the global variability, climate can change at a regional level too. Let us find out

more about this.o

Regional Variability

Regional VariabilityRegional or local climate is generally much more variable than climate on a hemispheric or

global scale because regional or local variations in one region are compensated for by opposite

variations elsewhere.

A good example for this kind of variability is the ENSO (El Niño Southern Oscillation).

ENSO (El Niño Southern Oscillation)

Source: NASA

It is a coupled phenomenon of ocean-atmosphere interaction. El Niño occurs in the Pacific

Ocean when there is a shift in ocean temperatures (towards warm) due to atmospheric

conditions in the tropical Pacific. These oceanic changes normally begin in December around

Christmas; hence the South Americans have named the phenomenon El Niño, meaning

‘Little Boy’. It has been observed that El Niño impacts weather patterns all over the

world. It occurs at regular intervals of about four years and primarily affects the Pacific coast of

South America, lasting for 8–10 months.

The Southern Oscillation is the see-saw pattern of reversing surface air pressure between the

eastern and western tropical Pacific; when the surface pressure is high in the eastern tropical

Pacific it is low in the western tropical Pacific, and vice-versa. Since the ocean warming and

pressure reversals are, for the most part, simultaneous, scientists call this phenomenon the El

Nino/Southern Oscillation or ENSO for short. 

Normally, the trade winds blow towards the west across the Pacific, pushing warm surface

water away from the South American coast and this leads to upwelling of nutrients along the

Peru coast. Along this coast, the cold water is rich in nutrients and supports a diversity of

marine life and provides a good catch of fish for fishermen around this part of the year. 

During an El Niño period, the winds slow down. Warm water accumulates at the surface and

causes significant reduction in the quantities of nutrients, plankton, and fish. This leads to

changes in weather patterns. A wide variety of disasters that have taken place all over the world

during these periods have been attributed to El Niño. When pressure is high in the Pacific

region, it tends to be low in the Indian Ocean, affecting the movement of the monsoon winds.

Thus, we find that natural climate variation manifests itself either globally or regionally. These

variations are caused by both internal and external factors. Common phenomena contributing to

climate variation include natural forcings, radiative forcing, greenhouse effect, and feedback

cycles.

Now, we will discuss the human-induced climate variation.

Human-induced Climate Variation: Human activities also influence the climate. The major

human-induced causes include changes in greenhouse gas (GHG) concentrations, changes

in aerosol levels, and changes in land use and land cover.o Enhanced Greenhouse Effect

Enhanced Greenhouse EffectMost human activities influence the climate by bringing about an increase in the concentration of greenhouse gases

in the atmosphere. An increase in the concentration of greenhouse gases leads to an increase in the magnitude of

the greenhouse effect. This is known asenhanced greenhouse effect.

The enhanced greenhouse effect is the direct result of human activities through processes such as the burning of

fossil fuels, industrial operations and forest clearing releasing carbon dioxide, methane and nitrous oxide into the

atmosphere. Chlorofluorocarbons, or CFCs, are also potent greenhouse gases, and as an added danger, they also

destroy the ozone layer.

A rough approximate of the contribution of GHGs is given in the following figures.

Global annual emissions of anthropogenic GHGs from 1970 to 2004

Share of different anthropogenic GHGs in total emissions in 2004

World Climate Zones

Have you ever wondered why one area of the world is a desert, another a grassland, and another a rainforest? Why are there different forests and deserts, and why are there different types of life in each area? The answer is climate.

Climate is the characteristic condition of the atmosphere near the earth's surface at a certain place on earth. It is the long-term weather of that area (at least 30 years). This includes the region's general pattern of weather conditions, seasons and weather extremes like hurricanes, droughts, or rainy periods. Two of the most important factors determining an area's climate are air temperature and precipitation.

World biomes are controlled by climate. The climate of a region will determine what plants will grow there, and what animals will inhabit it. All three components, climate, plants and animals are interwoven to create the fabric of a biome.

 

Some facts about climate

The sun's rays hit the equator at a direct angle between 23 ° N and 23 ° S latitude. Radiation that reaches the atmosphere here is at its most intense.

In all other cases, the rays arrive at an angle to the surface and are less intense. The closer a place is to the poles, the smaller the angle and therefore the less intense the radiation.

Our climate system is based on the location of these hot and cold air-mass regions and the atmospheric circulation created by trade winds and westerlies.

Trade winds north of the equator blow from the northeast. South of the equator, they blow from the southeast. The trade winds of the two hemispheres meet near the equator, causing the air to rise. As the rising air cools, clouds and rain develop. The resulting bands of cloudy and rainy weather near the equator create tropical conditions.

Westerlies blow from the southwest on the Northern Hemisphere and from the northwest in the Southern Hemisphere. Westerlies steer storms from west to east across middle latitudes.

Both westerlies and trade winds blow away from the 30 ° latitude belt. Over large areas centered at 30 ° latitude, surface winds are light. Air slowly descends to replace the air that blows away. Any moisture the air contains evaporates in the intense heat. The tropical deserts, such as the Sahara of Africa and the Sonoran of Mexico, exist under these regions.

 

Seasons

The Earth rotates about its axis, which is tilted at 23.5 degrees. This tilt and the sun's radiation result in the Earth's seasons. The sun emits rays that hit the earth's surface at different angles. These rays transmit the highest level of energy when they strike the earth at a right angle (90 °). Temperatures in these areas tend to be the hottest

places on earth. Other locations, where the sun's rays hit at lesser angles, tend to be cooler.

As the Earth rotates on it's tilted axis around the sun, different parts of the Earth receive higher and lower levels of radiant energy. This creates the seasons.

 

Köppen Climate Classification System

The Köppen Climate Classification System is the most widely used for classifying the world's climates. Most classification systems used today are based on the one introduced in 1900 by the Russian-German climatologist Wladimir Köppen. Köppen divided the Earth's surface into climatic regions that generally coincided with world patterns of vegetation and soils.

The Köppen system recognizes five major climate types based on the annual and monthly averages of temperature and precipitation. Each type is designated by a capital letter.

A - Moist Tropical Climates are known for their high temperatures year round and for their large amount of year round rain.

B - Dry Climates are characterized by little rain and a huge daily temperature range. Two subgroups, S - semiarid or steppe, and W - arid or desert, are used with the B climates.

C - In Humid Middle Latitude Climates land/water differences play a large part. These climates have warm,dry summers and cool, wet winters.

D - Continental Climates can be found in the interior regions of large land masses. Total precipitation is not very high and seasonal

temperatures vary widely.

E - Cold Climates describe this climate type perfectly. These climates are part of areas where permanent ice and tundra are always present. Only about four months of the year have above freezing temperatures.

Further subgroups are designated by a second, lower case letter which distinguish specific seasonal characteristics of temperature and precipitation.

f - Moist with adequate precipitation in all months and no dry season. This letter usually accompanies the A, C, and D climates.

m - Rainforest climate in spite of short, dry season in monsoon type cycle. This letter only applies to A climates.

s - There is a dry season in the summer of the respective hemisphere (high-sun season).

w - There is a dry season in the winter of the respective hemisphere (low-sun season).

To further denote variations in climate, a third letter was added to the code.

a - Hot summers where the warmest month is over 22°C (72°F). These can be found in C and D climates.

b - Warm summer with the warmest month below 22°C (72°F). These can also be found in C and D climates.

c - Cool, short summers with less than four months over 10°C (50°F) in the C and D climates.

d - Very cold winters with the coldest month below -38°C (-36°F) in theD climate only.

h - Dry-hot with a mean annual temperature over

18°C (64°F) in Bclimates only.

k - Dry-cold with a mean annual temperature under 18°C (64°F) in Bclimates only.

 

 

Major Climate Zones(Printing tip: Set printer to landscape.)

Zone Latitudes Sunlight Temperatures Precipitation

Tropics From Tropic of Capricorn (23.5 S latitude) to Tropic of Cancer (23.5 N latitude)

Direct sunlightHours and intensity don’t change much throughout the year.

Hot all year. Equator has rain in most seasons; Other parts of tropics have rainy summers and drier winters.  

Subtropics(Part of southern U.S. and much of Mexico)

From 23.5 N or S latitude to about 35 N or S latitude.

Intermediate between tropics and other regions.

Typically hot; can go from hot in  daytime to cold at night.

Often dry; most hot deserts are located here.

Temperate(Most of U.S. and Canada.)

From about 30 N latitude to about 65 N latitude (Arctic Circle); From 30 N latitude to about 65 N latitude (Antarctic Circle)

Fluctuates with the seasons. Hours and intensity are greater in summer,  less in winter.

Fluctuate with the seasons. 

The farther south and the closer to the ocean, the less they fluctuate. *

Precipitation in all seasons. Varies.

Polar From 60 degree N or S  Changes dramatically. Sun  The winters are  Very dry; little 

(Part of Canada and Alaska)

latitude to each pole. is never direct (stays low on horizon).Almost no light in winter; all light in summer. 

very cold and the summers cool to cold.

precipitation. Snow and ice cover year-round.

* Maritime temperate zone: Water holds heat longer than land does, so temperatures in locations near oceans don’t fluctuate as much during the year. These areas have cooler summers and warmer winters than inland regions. 

* Continental temperate zone: Areas in the middle of the continent, far from water, range widely in temperature. They often have very cold winters and hot summers. 

Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds to

the Köppen climate classification categories "Aw" and '"As."

Tropical savanna climates have monthly mean temperature above 18°C in every month of the year and

typically a pronounced dry season, with the driest month having precipitation less than 60 mm and also

less than (100 − [total annual precipitation {mm}/25]). This latter fact is in direct contrast to a tropical

monsoon climate, whose driest month sees less than 60 mm of precipitation but has more than (100 –

[total annual precipitation {mm}/25]). In essence, a tropical savanna climate tends to either see less

rainfall than a tropical monsoon climate or have more pronounced dry seasons.

There are generally four types of a tropical savanna climate:

One form of the tropical savanna climate features distinct wet and dry seasons of relatively equal

duration. Most of the region’s annual rainfall is experienced during the wet season and very little

precipitation falls during the dry season.

The second type of a tropical savanna climate features a lengthy dry season and a relatively short

wet season. This version features seven or more dry season months and five or less wet season

months. There are variations within this version. On one extreme, the region receives just enough

precipitation during the short wet season to preclude it from a semi-arid climate classification. This

drier variation of the tropical savanna climate is typically found adjacent to regions with semi-arid

climates. On the other extreme, the climate features a lengthy dry season followed by a short but

extremely rainy wet season. However, regions with this variation of the climate do not experience

enough rainfall during the wet season to qualify as a tropical monsoon climate.

The third type of a tropical savanna climate features a lengthy wet season and a relatively short dry

season. This version features seven or more wet season months and five or less dry season months.

This version’s precipitation pattern is similar to precipitation patterns observed in some tropical

monsoon climates. However, regions with this variation of the climate do not experience enough

rainfall during the wet season to qualify as a tropical monsoon climate.

The fourth, rarer form of the tropical savanna climate features a dry season with a noticeable amount

of rainfall followed by a rainy wet season. In essence, this version mimics the precipitation patterns

more commonly found in a tropical monsoon climate. However, regions with this version of the

climate fall short of a tropical monsoon climate categorization because it either does not receive

enough precipitation during the dry season, or it does not receive enough annual precipitation.

Tropical climateFrom Wikipedia, the free encyclopedia

Locations of tropical climates, with subtypes.

  Af—Tropical rainforest climate.

  Am—Tropical monsoon climate.

  Aw—Tropical savanna climate.

Beach in Naples, Florida lined with coconuttrees is an example of a tropical climate. Although it lies in the subtropics over a

hundred miles north of the tropic of cancer, the warm waters of theGulf of Mexico give it a monthly mean temperature never

under 18 °C (64 °F), classifying its climate as tropical.

Intertropical Convergence Zone vertical velocity at 500 hPa, July average in units of pascals per second. Ascent (negative

values) is concentrated close to the solar equator; descent (positive values) is more diffuse.

A tropical climate is a climate of the tropics. In the Köppen climate classification it is a non-arid climate in

which all twelve months have mean temperatures above 18 °C (64 °F). Unlike the extra-tropics, where there

are strong variations in day length and temperature, with season, tropical temperature remains relatively

constant throughout the year and seasonal variations are dominated by precipitation.

Contents

  [hide] 

1     Subtypes   

2     Intertropical Convergence Zone   

3     References   

4     External links   

Tropical rainforest climate (Af):[1] All twelve months have average precipitation of at least 60 mm

(2.4 in). These climates usually occur within 5–10° latitude of the equator. In some eastern-coast

areas, they may extend to as much as 25° away from the equator. This climate is dominated by

the Doldrums Low Pressure System all year round, and therefore has no natural seasons.

Tropical monsoon climate (Am):[1] This type of climate, most common in Southand Central America,

results from the monsoon winds which change direction according to the seasons. This climate has a

driest month (which nearly always occurs at or soon after the "winter" solstice for that side of the

equator) with rainfall less than 60 mm, but more than (100 − [total annual precipitation {mm}/25]).

Tropical wet and dry or savanna climate (Aw):[1] These climates generally have a pronounced dry

season, with the driest month having precipitation less than 60 mm and also less than (100 − [total

annual precipitation {mm}/25]).

Temperate climateFrom Wikipedia, the free encyclopedia

For the usage in virology, see temperateness (virology).

This article needs additional citations for verification. Please help improve this article byadding citations to reliable sources. Unsourced material may be challenged and removed.(January 2013)

Part of the nature series

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Temperate climate (shown in green in the map)

In geography, temperate or tepidlatitudes of the globe lie between thetropics and the polar regions. The

changes in these regions betweensummer and winter are generally relatively moderate, rather than extreme

hot or cold.

However, in certain areas, such asAsia and central North America, the variations between summer and winter

can be extreme because these areas are far away from the sea, causing them to have a continental climate. In

regions traditionally considered tropical, localities at high altitudes(e.g. parts of the Andes) may have a

temperate climate.

The north temperate zone extends from the Tropic of Cancer (at about 23.5 degrees north latitude) to

the Arctic Circle (at approximately 66.5 degrees north latitude). The south temperate zone extends from

the Tropic of Capricorn (at approximately 23.5 degrees south latitude) to the Antarctic Circle (at approximately

66.5 degrees south latitude). [1][2]

In a very broad sense, temperate climate also includes a subtropical climate, variants: subtropical

semidesert/desert, humid subtropical, oceanic subtropical and Mediterranean climate. However, a typical

temperate climate is one of the four climate zones in the world, beside polar regions (subarctic climate, arctic

climate, tundra climate,ice cap climate) and the subtropics, tropics.

The maritime climate is affected by the oceans, which help to sustain somewhat stable temperatures

throughout the year. In temperate zones the prevailing winds are from the west, thus the western edge of

temperate continents most commonly experience this maritime climate. Such regions include Western Europe,

and western North America at latitudes between 40° and 60° north (65°N in Europe).

Continental, semi-arid and arid are usually situated inland, with warmer summers and colder winters. Heat

loss and reception are aided by extensive land mass. In North America, the Rocky Mountains act as a climate

barrier to the maritime air blowing from the west, creating a semi-arid and continental climate to the east.[3][4]

[5] In Europe, the maritime climate is able to stabilize inland temperature, because the major mountain range –

the Alps – is oriented east-west (the area east of the long Scandinavian mountain range is an exception).

The vast majority of the world's human population resides in temperate zones, especially in the northern

hemisphere because of the mass of land.[6]

The temperate climate refers to zones in a range of latitudes between 40° and 60/70°. No as hot as the subtropical climate and milder than the polar climate, it is usually defined but by what it is not.

A sub-type is the moderate oceanic climate oceanic : windy and without excessive temperatures, which characterizes the Western shores of Europe. The four seasons are well marked. In these climate zones you tend to find a wide range of architecture as well due to the need for housing that can with stand both the cold and snow as well as the summer heat. Common place in these dwellings is to have both air conditioning systems and heating systems as well as ceiling fans with lights to help circulate the air. It is associated by leafy tree forests and meadows. It alternates relatively fresh summers with mild and wet winters.

Another sub-type is the continental moderate climate which dominates the steppes. It is cold and dry in winter while being rather hot and rainy in the summer. There are frequent storms and the transition of seasons are short. The hypercontinental climate has short summers and dry and very cold winters. It extends over Siberia, Alaska and Canada which are covered with coniferous tree forests. ·

Polar and highland climates

temperature is key (again)

• cold due to limited solar radiation

• low angle of incidence of insolation

Moisture is relatively scarce all the time

except where oceans intercede

Annual fluctuation is much greater than diurnal changes

Earth - Sun relationships