Heat and Air Temperature Earth Science Mr. Bimber

What factors affect air Temperature? Insolation (incoming solar radiation) Clouds Water Elevation Ground surface

Insolation: latitude Higher latitudes get the sun’s rays at a low angle, so they’re spread out over a greater area. Near the equator, the sun’s energy is greater.

Insolation: time of day Morning and evening sun are at a lower angle.

Insolation: time of year Earth’s axis tilt: the sun’s rays hit at a lower angle in winter than in summer.

Cloud cover: daytime Clouds reflect more of the sun’s rays.

Cloud cover: night Heat rays from earth are reflected back more on cloudy nights. Clear nights get colder.

Water Water has a high specific heat. It takes more energy, and longer to heat up or cool down than land.

Water nearby Temperature changes much less downwind of oceans and large lakes.

No water nearby… Temperature changes a lot in dry regions far away from oceans or large lakes.

Water releases heat when… heat energy is released when water condenses from gas to liquid, or freezes.

Water releases heat when… Air in clouds warms when they rain or snow, so they rise higher because of convection. That’s why these thunderclouds are tall.

Water releases heat when… Night air is warmed when water condenses as dew or frost. It doesn’t usually get much colder than the “dew-point temperature”.

Water absorbs heat when… Air gets cooled when its heat energy is needed to melt ice or evaporate liquid water. (Sweden’s “Ice Hotel” is built every December; still melting in May.)

Elevation The higher you go, the colder it gets.

Ground cover Dark surfaces, like asphalt roads and rooftops absorb more heat than light colored surfaces.

Why is this rooftop green? It saves energy and money. Plants help cool the air through evaporation.

Humidity Humidity is the amount of water vapor in the air. Warm air can hold more water vapor than cold air.

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

Humid air feels warmer. Your body cools itself by evaporating perspiration. When it’s humid, less water evaporates from your skin, so you can’t cool down as well as you can in dry air.

Humidity can affect temperature. When relative humidity goes over 100%, fog, dew, or frost forms. These release heat energy to the air, warming it.

What is “wind chill”? Wind carries your body heat away, and helps water evaporate from your skin, cooling it. The “wind chill” is what the temperature feels like because of the wind.

Temperature factors Factors affecting it: Insolation Clouds Water Elevation Ground cover Factors affecting how cold we feel: Humidity wind