A. Early atmosphere • Created from gases released from volcanoes – outgassing. • Mostly water vapor, nitrogen, and carbon dioxide. • Oxygen was not part of atmosphere until a long time later • The presence of newly formed green algae and plants released oxygen into the atmosphere.
B. Composition of Atmosphere • Mostly made of nitrogen and oxygen • Nitrogen = 78% • Oxygen = 21% • A few other gases are present in small amounts.
C. 4 Layers • Troposphere • Stratosphere • Mesosphere • Thermosphere
D. Troposphere • Closest layer and the layer we live in! • Clouds, wind, rain, and snow • Densest • Why? • Temperature decreases as altitude increases • Temperature stops decreasing – tropopause*
E. Stratosphere • 2nd layer • Oxygen (O2)-deficient; no H20 vapor • Temperature increases as altitude increases • Why does it get hotter? • ozone layer –upper stratosphere • What does ozone protect us from? • What is molecular formula for ozone? • Temperature stops increasing at - stratopause
F. Mesosphere • 3rd layer • Temperature decreases as altitude increases • No gases that absorb the sun’s radiation. • Coldest layer ~ -80°C*
G. Thermosphere • Temperature increases as altitude increases • Oxygen and nitrogen in this layer absorb sun’s radiation • Hottest layer ~980°C • Convert to Farhenheit • Tf = 32 + 9/5 Tc Tf = 32 + 9/5 (980) Tf = ? 1796° F • Outer portion= exosphere
H. Ionosphere • Electrically charged ions; solar radiation • What is ion? • Positively charged ion? • Upper mesosphere and lower thermosphere • Helpful in radio communication
Air Pressure • Atmospheric pressure – pressure due to weight of atmosphere • Sea level- 14.7 pounds per square inch. 3. The more air above you, the greater the air pressure. a. Higher air pressure in Valley, than in the mountains. • Mercury barometer
III. Human Influence on Atmosphere • Clorofluorocarbons (CFC’s) destroy ozone molecules. • Already a hole in ozone near south pole. • Ozone is getting thinner. • Excess carbon dioxide leads to greenhouse effect • Transportation vehicles responsible for ½ of pollutants in air. • Sun’s radiation trapped – global warming • What effect can global warming have on environment?
Solar radiation • Some radiation is reflected by clouds • Pollution from cars and factories release carbon dioxide. • Heat is released towards atmosphere. Some escapes, some is trapped by greenhouse gases.