respiration The process in which animals and plants use oxygen and produce carbon
dioxide; in respiration, organisms convert sugar into food energy they can use.
water vapor The gas form of water.
weather The temporary state of the atmosphere in a region; the weather in a location
depends on the air temperature, humidity, precipitation, wind and other features of
the atmosphere.
Points to Consider
- How would Earth be different if it did not have an atmosphere?
- What are the most important components of the atmosphere?
- How does the atmosphere vary with altitude?
15.2 Atmospheric Layers.
Lesson Objectives
- List the major layers of the atmosphere and their temperatures.
- Discuss why all weather takes place in the troposphere.
- Discuss how the ozone layer protects the surface from harmful radiation.
Introduction
The atmosphere is layered, and these layers correspond with how the atmosphere’s temper-
ature changes with altitude. By understanding the way temperature changes with altitude,
we can learn a lot about how the atmosphere works. For example, the reason that weather
takes place in the lowest layer is that the Earth’s surface is the atmosphere’s primary heat
source. Heating the lowest part of the atmosphere places warm air beneath colder air, an
unstable situation that can produce violent weather. Interesting things happen higher in the
atmosphere, like the beautiful aurora, which light up the sky with brilliant flashes, streaks
and rolls of white or colored light.
Air Temperature
Warm air rises: that’s a saying just about everyone has heard. But maybe not everyone
knows why this is true. Gas molecules are free to move around, and the molecules can take
up as much space as they need. When the molecules are cool, they are sluggish and do