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Meteorology (Weather)

Follow along in your notes packet…

http://www.youtube.com/watch?v=FMagDRCpJ14

http://www.youtube.com/watch?v=tkK4_F0VKhM

Our atmosphere has 3 states of water: 1. Ice 2. Water 3. Water Vapor

Changing Forms of Water

Water changes from one phase to another as heat energy is either absorbed or released.

We call this heat energy latent heat Most water enters our atmosphere

through Evaporation The process in which a solid changes

directly into a gas is Sublimation

Changing Forms of Water

Water Vapor in the atmosphere, known as humidity, is controlled by rates of evaporation and condensation

Temperature often controls the rate of evaporation, where as the rate of condensation is determined by vapor pressure

When the rate of evaporation and condensation are in equilibrium, the air is “saturated”

Humidity

Absolute Humidity is the mass of water vapor contained in a given volume of air (the actual amount of water vapor in the air)

Relative Humidity is a ratio of actual water vapor content of the air to the amount of water vapor needed to reach saturation

We use a Psychrometer to measure humidity

Video

Relative & Absolute Humidity

Air moves from areas of high pressure to low pressure

The Coriolis Effect occurs when winds are deflected by Earth’s rotation

Air masses are large bodies of air throughout which temperature and moisture content are similar

How Air Moves

Air masses are classified according to their source regions, which are determined by the temperature and humidity of the air masses

Cold Air Masses: Polar areas Warm Air Masses: Tropical areas Masses formed over oceans: Maritime

(moist) Masses formed over land: Continental

(dry)

Types of Air Masses

A cool air mass is dense and won’t mix with a less dense and warm air mass- a boundary called a front forms

between the masses Video

Types of Fronts

Cold Front: a cold air mass overtakes a warm air mass. Cold air lifts the warm air

Storms formed from a cold front are short-lived and sometimes violent

If it is a slow moving cold front, the storm may be weak with light precipitation

Types of Fronts

Warm Front: a warm air mass overtakes a cold air mass

Generally produces precipitation over a large area and may sometimes cause violent weather

Types of Fronts

Stationary Front: air masses move very slowly or not at all

Weather produced is similar to a warm front

Occluded Front : when a fast moving cold front overtakes a warm front and lifts the warm air off the ground completely

Types of Fronts

Thunderstorms produce thunder and lightning.

Clouds discharge electricity in the form of lightning.

The upper part of the cloud carried a positive charge, the lower part carries the negative charge.

Lighting is the huge spark that travels within the cloud or between the cloud and ground to equalize the electrical charges

Severe Weather: Thunderstorms

Thunderstorms have 3 stages: 1. Cumulus Stage 2. Mature Stage 3. Dissipating Stage

Severe Weather: Thunderstorms

Hurricanes: severe storm that forms over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely low pressure storm center

Most destructive storms on Earth Cause rising in the sea levels with large

waves called storm surge

Severe Weather: Hurricanes

To rate a hurricane we use the Saffir-Simpson Scale: 5 categories based on central pressure, wind speed, and storm surge.

Category 1: least damage Category 5: most damage Hurricanes begin over warm

water….how would Global Climate Change affect this?

Severe Weather: Hurricanes

Shortest lived severe storms, destructive, rotating column of air that has very high wind speeds and that may be visible as a funnel-shaped cloud

Forms when a thunderstorm meets high-altitude, horizontal winds which cause the rising air in the thunderstorm to rotate. A storm cloud may develop a narrow, funnel-shaped, rapidly spinning extension that reaches downward

Severe Weather: Tornadoes

To measure and indicate temperature we use a Thermometer

For changes in air pressure affect air masses at certain locations or atmospheric pressure we use a Barometer

Wind speed is measured with an Anemometer

Wind directed is measure with a Wind Vane Radar, weather satellites and computers are

useful as well

Weather Instruments

Meteorologists and weather stations collect data and transfer it onto weather maps.

So that everyone around the world can understand they use symbols and colors

A cluster of weather symbols are called a station model: pattern of symbols that represent the weather at a particular observing station and is transferred onto a weather map

Forecasting the Weather

Isotherms: lines that connect points of equal temperature (think: thermometer)

Isobars: lines that connect points of equal atmospheric pressure (think: barometer)

Centers marked with an “H” represent high pressure; “L” is for low pressure

Areas with precipitation are marked with colors or symbols

Plotting Temp & Pressure

Doppler Radar & Satellite Images can tell us about intensity and precipitationso that meteorologists can create weather models

Types: Daily Forecasts: predict weather for 48 hrs Extended Forecast: 3-5 days Long-Range Forecast: more than 7 days Watch: conditions are ideal for severe weather Warning: severe weather has been spotted OR

is predicted within 24 hours

Weather Forecasts

Weather conditions for an area over a long period of time is Climate

Different latitudes receive different amounts of solar energy

The higher the latitude, the smaller the angle at which the Sun’s rays hit the Earth and the smaller the amount of solar energy received by the area

The tilt of Earth’s axis is also a factor

Climate

Topography: surface features of the land can control the flow of air through a region

Rain Shadow: moving air mass encounters a mountain range, the air mass rises, cools and loses most of its moisture through precipitation. The air that flows down the other side is usually warm and dry.

Warm winds that flows down the eastern slopes of the Rocky Mountains are Chinooks

Topography

Tropical Climates: high temperatures and heavy precipitation during at least part of the year

Middle- Latitude Climates: has an average maximum temperature below 18 degrees C in the coldest month and an average minimum temperature above 10 degrees C in the warmest month

Tropical Desert Climates: dry climates that receive less than 40 cm of precipitation a year

Climate Zones

Mediterranean Climate: mild climate that has a small temperature range between summer and winter

Tundra Climate: smaller annual temperature range than subarctic but has a colder climate

Polar Icecap: much of the land and ocean covered in thick sheets of ice, average temp never rises above freezing

Large bodies of water, such as lakes, can influence local climates as well as precipitation

Climate Zones