Chapter 3

Atmospheric Energy and

Global Temperatures

Earth’s Energy Balanceor:

What comes in must go out! The sun is the power source that

drives many of Earth’s flow systems (storms, waves, ocean and wind currents)

When the sun’s energy (sunlight) enters our atmosphere, its inputs must be balanced by equal outputs

This energy must be redistributed over the globe to maintain the conditions of our current lifelayer

Net Radiation Net radiation is the difference between the

radiation energy surplus and deficit Can be measured daily, monthly, yearly, even

by century, in order to help us answer the question, “Are we heating up or cooling down?”

Determining net radiation begins with a number of insolation losses in the atmosphere…

Surplus vs. Deficit

A surplus in your checkbook is a good thing!

A surplus of energy within Earth’s systems generally means an increase in

temperature and changes in Earth’s systems’ circulations

(NOT such a good thing!)

Hypothetical Radiation Balance

Reflection

Albedo—the % of insolation reflected back to space

Scattering

Hypothetical Radiation Balance

Conduction

Convection

Convection

Hypothetical Radiation Balance

Counterradiation

The Greenhouse Effect

Hypothetical Radiation Balance

The Redistribution of Energy Sensible heat transfer Latent heat transfer

Sensible heat is heat that can be felt and measuredMoved by conduction; transferred by global

winds and ocean currents

Sensible Heat

Latent Heat Latent heat cannot be sensed or directly

measuredHeat that is stored or released during the change of

state of solids, liquids, and gasesMovement occurs most often through condensation

and evaporation (Ex.: the formation of clouds or the evaporation of ocean water)

Water in the atmosphere is the most important mover of latent heat, which ultimately helps to balance Earth’s energy budget

Review1.What is the power source that drives

Earth’s flow systems?2.What happens if Earth’s energy inputs

and outputs are unbalanced?3.Describe the different ways incoming

solar radiation is balanced by outgoing radiation (draw a diagram, if that makes it easier to explain).

4.What is albedo? What kinds of surfaces have a high albedo? What surfaces have a low albedo?

5.Describe convection.6.What is counterradiation? What kinds

of gases contribute to counterradiation? What is the greenhouse effect?

7.What is the difference between sensible heat and latent heat?

Temperature

Temperature—a measure of the level of sensible heat of matter; an expression of atomic motionHeat moves from substances of higher temp.

to substances of lower temp. until their temperatures equalize

Fahrenheit, Celsius, and Kelvin Three systems of temperature

measurement in use internationally: Fahrenheit, Celsius, and Kelvin

In order to convert from Fahrenheit to Celsius and back, use these formulae:

C° = 5/9 (F-32°) F° = 9/5 C + 32°

0°K = absolute zero—the point at which all molecular motion ceases

-273.15°C or -459.67°FRoom temperature is about 295KConverting K to °C only requires adding

273° (e.g. 3°C = 276K)Especially useful when dealing with

very low temperatures, as there are no negative numbers

Isotherms

Isotherms—lines on a map that connect points of equal temperature

Daily and SeasonalTemperature Changes Daily temperatures are influenced by

patterns of sunrise and sunset, which are the result of seasonal changes, themselves the result of latitude.

Daytime Temperatures:Normal Condition

Temperature Inversions Temperatures are generally

hotter during the day at the surface and cooler above.

A temperature inversion occurs when surface temperatures are cooler than the air above for some vertical distance.

Once a temperature inversion occurs, it tends to persist until all heat has been transferred back out to space.

There are four common types of temperature inversions….

Subsidence Inversion Subsidence inversions

Occur in the upper atmosphereResult of air slowly descending due to a high pressure

cellAs the air descends, it compresses and warms, and

this warm layer sits atop cooler air belowMost common in the subtropics year-round and in the

Northern Hemisphere in winterDo not sink lower than a few hundred meters above

sea level due to low-level turbulence

Radiational Inversion

Radiational inversions—the result of rapid radiational coolingMost common in high latitudes, especially at

night Long wave radiation (heat) is radiated back

out to space and has left the lower portion of the troposphere, but has not yet entirely left the air above.

Advectional Inversion Advection = “wind” (any horizontal

movement of air, usually in response to atmospheric pressure differences)

Advectional inversions—a horizontal flow of air displaces warmer air upwardEspecially common along coasts, as air moves

out of high pressure zones over the water and into a low pressure zone over land.

Filmore, CA

Cold-air-drainage Inversion Cold-air-drainage inversions—cooler air on mountain

slopes sinks into a valley below, forcing the warmer air in the valley to rise upward

Most common in the midlatitudes, especially in winter

Daily Temperature Lags Insolation levels rise as the sun rises, reach a

maximum at noon, then decrease and end at sunset

The coldest time of day is actually after the sun has risen

The hottest time of day is a few hours after noon The hottest time of day (maximum daily

temperature) varies based on such factors as cloudiness, windiness, proximity to a large body of water, and even storms.

Seasonal Temperature Lags In summer, monthly insolation is highest In winter, monthly insolation is lowest In between, during the equinoxes, insolation levels are in

the middle Highest monthly temperatures tend to be one month after

the summer solstice Lowest monthly temperatures also follow one month after

the winter solstice Although radiation levels are similar for both the fall

(autumnal) and spring (vernal) equinoxes, temperatures are considerably warmer following the summer months than following winter. The temperatures of the equinoxes are not the same because each reflects the temperatures of previous seasonal conditions.

Factors influencing differences in temperature Latitude Elevation/Altitude Cloud Cover and Albedo Proximity to a Water Body

Differential heating of land and waterOcean currents

Proximity to an urban area

January—Global TemperaturesLatitude

July—Global TemperaturesLatitude

Elevation As discussed previously…

Remember the ELR!

Cloud Cover and Albedo

Distribution of Land and Water: Properties of Land vs.

Water

Proximity to a Water Body:Isotherms on a Hypothetical Continent

Proximity to a Water Body:Exterior (Coastal) vs. Interior (Continental) Locations

Latitude and Oceans

Ocean Currents

General Circulation of the Oceans

Proximity to an Urban Area:The Urban Heat Island

Global Temperature Patterns: Mini Quiz! Which will be colder? Highland areas (areas of higher elevation) or

lowland areas in the same region? Highlands are colder than surrounding lowlands.

Does temperature increase or decrease with latitude (getting closer to 90°N or S)? It decreases.

True or False? Seasonal isotherm shifts are more dramatic over land areas than over oceans. True

Which influences temperatures on the edges of continents: warm or cold ocean currents? Both warm and cold currents affect temperatures on nearby

land Equatorial locations receive an even amount of insolation year

round. How does that affect their temperature patterns?They tend to have more even temperature patterns

Review1.What is the difference between heat and

temperature?2.True or False? Heat flows from the hot object

toward the cold object until both objects are the same temperature.

3.Lines on a map that connect points of equal temperature are called...

4.Draw two graphs: one showing a normal atmospheric temperature condition and one showing a temperature inversion.

5.Describe the 4 temperature inversions.

6.The hottest time of day is just after noon and the coldest time is just after sunrise. Why?

7.Name the 5 factors influencing the temperature of any location.

8.Why does being near a body of water make a location warmer in winter and cooler in summer than locations further inland? (Remember the properties of land vs. water!)

9.What is an urban heat island?