1. Composition of the Atmosphere  A mixture of chemical elements and compounds: –Nitrogen (N 2 ) ~ 78% –Oxygen (O 2 ) ~ 21% –Other gases ~ 1%

2. Layers of the Atmosphere

3.  Thermosphere - the atmospheric layer above the mesosphere.  Mesosphere - coldest layer of the atmosphere that extends upward from the stratosphere to an altitude of about 80 km.  Stratosphere - layer of the atmosphere that extends upward from the troposphere to an altitude of 50 km; contains most atmospheric ozone.  Troposphere - atmospheric layer closest to the earth’s surface where nearly all weather occurs.

4. Air Pollution  Temperature Inversion – atmospheric condition in which warm air traps cooler air near the earth’s surface.

5. Conduction, Convection and Radiation  Conduction – type of energy transfer in which vibrating molecules pass heat along to other vibrating molecules by direct contact.  Convection – transfer of heat through the movement of a fluid material.  Radiation - energy that is radiated or transmitted in the form of rays or waves or particles.

6. Barometers  Units of Standard Atmospheric Pressure: –760 mm –29.92 in of Mg –1 atmosphere –1000 millibars (mb) Mercurial Barometer Mercurial Barometer

7. Energy Transfer in the Atmosphere  Conduction – direct contact  Convection – movement of a fluid, such as air  Radiation – no direct contact

8. Which is Which?

9. The Atmosphere and Solar Radiation  About 70% of the solar energy that reach Earth is absorbed by land, water, and atmosphere. 30% is reflected back into space. –Scattering – deflection of solar radiation –Albedo – percentage of solar radiation reflected off a surface  Earth’s total albedo = 30%

10. The Greenhouse Effect and Global Warming  How are people speeding up the Greenhouse Effect? –Pollution –Cars –Factories –Increased population –Cutting down trees –Burning fossil fuels  Are people causing global warming and the greenhouse effect?