Heat and Air Heat and Air TemperatureTemperature

Earth ScienceEarth ScienceMr. BimberMr. Bimber

What factors affect air What factors affect air Temperature?Temperature?

Insolation (incoming solar radiation)Insolation (incoming solar radiation) CloudsClouds WaterWater ElevationElevation Ground surfaceGround surface

Insolation: latitudeInsolation: latitude

Higher latitudes get the sun’s rays at a low angle, Higher latitudes get the sun’s rays at a low angle, so they’re spread out over a greater area. so they’re spread out over a greater area.

Near the equator, the sun’s energy is greater.Near the equator, the sun’s energy is greater.

Insolation: time of dayInsolation: time of day

Morning and Morning and evening sun are at evening sun are at a lower angle. a lower angle.

Insolation: time of yearInsolation: time of year

Earth’s axis tilt:Earth’s axis tilt:

the sun’s rays hit the sun’s rays hit

at a lower angle at a lower angle

in winter in winter

than in summer.than in summer.

Cloud cover: daytimeCloud cover: daytime

Clouds reflect more Clouds reflect more

of the sun’s rays.of the sun’s rays.

Cloud cover: nightCloud cover: night

Heat rays from earth Heat rays from earth

are reflected back are reflected back more more

on cloudy nights.on cloudy nights.

Clear nights get Clear nights get colder.colder.

WaterWater

Water has a high Water has a high

specific heat.specific heat.

It takes more energy,It takes more energy,

and longer to heat and longer to heat upup

or cool down than or cool down than land.land.

Water nearbyWater nearby

Temperature Temperature changes changes

much less downwind much less downwind of of

oceans and large oceans and large lakes.lakes.

No water nearby…No water nearby…

Temperature Temperature changes changes

a lot in dry regions a lot in dry regions far far

away from oceans oraway from oceans or

large lakes.large lakes.

Water releases heat when…Water releases heat when…

heat energy is heat energy is

released when released when

water condenses water condenses

from gas to liquid, from gas to liquid,

or freezes.or freezes.

Water releases heat when…Water releases heat when…

Air in clouds warms Air in clouds warms

when they rain or when they rain or snow,snow,

so they rise higher so they rise higher

because of because of convection.convection.

That’s why theseThat’s why these

thunderclouds are tall.thunderclouds are tall.

Water releases heat when…Water releases heat when…

Night air is warmedNight air is warmed

when water when water condensescondenses

as dew or frost.as dew or frost.

It doesn’t usually getIt doesn’t usually get

much colder than themuch colder than the

““dew-point dew-point temperature”.temperature”.

Water absorbs heat when…Water absorbs heat when…

Air gets cooled when its Air gets cooled when its

heat energy is needed heat energy is needed

to melt ice or evaporate to melt ice or evaporate

liquid water.liquid water.

(Sweden’s “Ice Hotel” is(Sweden’s “Ice Hotel” is

built every December;built every December;

still melting in May.)still melting in May.)

ElevationElevation

The higher you The higher you go, go,

the colder it the colder it gets.gets.

Ground coverGround cover

Dark surfaces, Dark surfaces,

like asphalt roads like asphalt roads

and rooftops and rooftops

absorb more heat absorb more heat

than light coloredthan light colored

surfaces.surfaces.

Why is this rooftop green?Why is this rooftop green?

It saves energy andIt saves energy and

money.money.

Plants help cool the Plants help cool the airair

through evaporation.through evaporation.

HumidityHumidity

Humidity is the Humidity is the amount of water amount of water vapor in the air.vapor in the air.

Warm air can hold Warm air can hold more water vapor more water vapor than cold air.than cold air.

Relative humidityRelative humidity

Relative humidity Relative humidity is the percent is the percent humidity compared humidity compared to the humidity to the humidity limit at the current limit at the current temperature.temperature.

Humid air feels warmer.Humid air feels warmer.

Your body cools itself Your body cools itself by evaporating by evaporating perspiration. perspiration.

When it’s humid, less When it’s humid, less water evaporates water evaporates from your skin, so you from your skin, so you can’t cool down as can’t cool down as well as you can in dry well as you can in dry air.air.

Humidity can affect Humidity can affect temperature.temperature.

When relative humidity When relative humidity goes over 100%, goes over 100%,

fog, dew, or frost forms. fog, dew, or frost forms.

These release heat These release heat energy to the air, energy to the air, warming it.warming it.

What is “wind chill”?What is “wind chill”?

Wind carries your body heat away, and Wind carries your body heat away, and helps water evaporate from your skin, helps water evaporate from your skin, cooling it.cooling it.

The “wind chill” is what the temperature The “wind chill” is what the temperature feels like because of the wind.feels like because of the wind.

Temperature factors Temperature factors

Factors affecting it:Factors affecting it:– InsolationInsolation– CloudsClouds– WaterWater– ElevationElevation– Ground coverGround cover

Factors affecting Factors affecting how cold we feel:how cold we feel:– HumidityHumidity– windwind