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Energy, Atmosphere and Land
Layers of the Atmosphere
What’s air made of?
Free Fall from the Edge of Space
One important feature of each of the four layers of the atmosphere
Troposphere (0-10km) – weather occurs here, well mixed, breathable, cools with increasing altitude Stratosphere (10-50km) – atoms sorted by mass, warms with increasing altitude, ozone layer Mesosphere (50-90km) – meteors burn up here, cools with increasing altitude, top part is ionized Thermosphere (above 90km) – ionized gases, aurora occurs here, warms with increasing altitude, reflects radio waves
Window to the Universe
How does the land heat up?
Land has a low specific heat capacity which means it heats up rather quickly with solar radiation (in contrast to water, which heats up slowly) Heat is absorbed in first few centimeters of land Geothermal Energy
How does the air heat up? Conduction: energetic molecules in land and water collide with molecules of air at surface which warms it up Convection: the warm air at surface becomes less dense and starts to rise causing cooler air to sink to surface and be warmed Radiation: water vapor and CO2 absorb the wavelengths emitted by earth (infrared)
What causes wind? Uneven heating of the air
Air with a lot of water in it heats more slowly than dry air, but it also holds on to it longer (humidex – how hot air feels like when it is humid) Air warms up and becomes less dense. Cooler air exerts pressure on warm air and moves it upward Convection currents north to south (horizontal) and low to high (vertical)
Sea breeze - Nighttime:
Sea breeze - Daytime: Land is warmer than water, it rises and cool air moves in from the water causing a breeze to come in off the water Warm air cools as it rises and sinks again to cause a convection current Sea breeze - Nighttime: Land cools faster than water, therefore the air over the water is now warmer and rises. Cool air from the land moves in to replace the warm air, causing a convection current
Land and Seabreezes Unequal heating of air over land and water results in breezes near shorelines. While the land is warm during the day, air above it rises, and a cool breeze blows in from the sea. As the land cools off at night, air pressure over it increases, and a cool land breeze blows out to the sea.
Sample Questions Explain why the temperature of dry land increases faster during the day and decreases faster during the night than the temperature of the water in lakes, rivers and oceans. A: Dry land changes its temperature faster than surrounding water because it has a smaller specific heat capacity.
Explain the role of conduction in heating of air.
A: Air is heated near a surface that absorbs solar energy (earth) by conduction. This warmer air moves up and cool air moves in to replace it and become warmed.
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