PDS AP Environmental Science 5th Period 2010-11

What’s Really in our Atmosphere?

In order to understand biomes, we have to understand why temperature and precipitation change in different places around the world. To start the understanding of this we talked about the composition and structure of the Earth’s atmosphere.

I: Composition-

• 78% Nitrogen- stable, inert gas because of the triple bond between the two nitrogen, does not help or harm organisms when they breath it in.
• 21% Oxygen- highly reactive
• 1%- Variable gases: water, {carbon dioxide, methane, nitrous oxide} warming gases, ozone

II: Structure- 4 basic layers- highest to lowest

• Thermosphere
• Mesosphere
• Stratosphere- contains the ozone layer which is blocks u.v. rays and is called “global sunscreen”
• Troposphere- called the “weather maker” because all weather occurs in this layer of atmosphere
• As you move higher in the atmosphere the atmospheric pressure goes down

http://www.aerospaceweb.org/question/atmosphere/atmosphere/layers.gif

One other important thing to know in order to understand biomes is the difference between climate and weather because climate is the reason for different biomes, not weather.

Climate v.s. Weather

Climate- regional, years/decades, occurs in upper troposphere and lower stratosphere: driven by the sun and the composition of the Earth

Weather- local, hour/day/week, occurs in lower troposphere: driven by climate