Earth’s Atmosphere

Atmosphere= a thin layer of air that protects the Earth’s surface from extreme temperatures and harmful Sun rays

Early atmosphere was much different than today. Volcanoes produced nitrogen and carbon dioxide, but little oxygen. More than 2 billion years ago simple organisms began producing oxygen. Eventually oxygen formed an ozone layer that protected Earth from harmful rays. Green plants and diverse life forms developed.

ü  Atmospheric makeup—mixture of gases, solids, and liquids

1.  Gases include nitrogen (78%), oxygen (21%), carbon dioxide, water vapor, and argon.

vAtmosphere is changing with the introduction of pollutants: increasing human energy use is increasing the amount of Carbon dioxide

vPollutants mix with oxygen and other chemicals to form smog

2.  Solids include dust, salt, and pollen.

3.  Liquids include water droplets and droplets from volcanoes.

ü  Five layers

1.  Troposphere

·      lowest layer

·      where humans live

·      extends about 10 km up

·      contains most of the water vapor and gases

·      warmed primarily by the Earth’s surface

·      Temperature decreases as altitude increases in this layer

       2.  Stratosphere

·      Extends 10 km to 50 km above Earth

·      Contains higher levels of ozone

§      Ozone layer is about 19 to 48 km above the earth.

§      3-atom oxygen molecules

§      Protects the Earth from the Sun’s harmful Ultraviolet radiation

§      Pollutants caused CFC’s (chlorofluorocarbons) are destroying the ozone layer

vCFC’s are used in refrigerators, air conditioners, aerosol sprays, and foam packaging

vIf these products develop a leak, CFC’s can enter the atmosphere

·      Temperatures increase as altitude increases

3.  Mesosphere

·      Extends from 50 km to 85 km

·      The layer in which shooting stars are visible

·      Temperatures decrease with altitude

4.  Thermosphere    

·      Thickest part of the atmosphere

·      85 km to 500 km

·      High temperatures

·      Contains the ionosphere= a layer of charged particles that can help carry radio waves

·      Very warm because the thermosphere and exosphere are the first to receive the Sun’s rays

5.  Exosphere

·      Outer layer of atmosphere

·      very few molecules

·      Space shuttle flies here

·      Very warm because the thermosphere and exosphere are the first to receive the Sun’s rays

ü  Atmospheric pressure—molecules closer to the surface are more densely packed (at higher pressure) together than those higher in the atmosphere because of the mass of gases pressing down on them from higher in the atmosphere.

 Water Cycle (Hydrologic Cycle)

http://epa.gov/climatechange/kids/water_cycle_version2.html

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/home.rxml

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/evap.rxml

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/cond/home.rxml

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/cond/conv.rxml

Wind= air in motion

What causes wind= as the sun warms the surface, the atmosphere warms, too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive less indirect rays, so the climate is colder. Warm air weighs less than cold air, so it rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.