I. Structure and Characteristics of the Atmosphere

A. Early atmosphere

1. Created from gases released from volcanoes – outgassing.

a. Mostly water vapor, nitrogen, and carbon dioxide.

2. Oxygen was not part of atmosphere until a long time later

a. The presence of newly formed green algae and plants released oxygen into the atmosphere.

B. Composition of Atmosphere

1. Mostly made of nitrogen and oxygena. Nitrogen = 78%b. Oxygen = 21%c. A few other gases are present in

small amounts.

C. 4 Layers

1. Troposphere2. Stratosphere3. Mesosphere4. Thermosphere

D. Troposphere

1. Closest layer and the layer we live in!2. Clouds, wind, rain, and snow 3. Densest

• Why?4. Temperature decreases as altitude

increases5. Temperature stops decreasing –

tropopause*

E. Stratosphere

1. 2nd layer 2. Oxygen (O2)-deficient; no H20 vapor3. Temperature increases as altitude

increases1. Why does it get hotter?

4. ozone layer –upper stratosphere1. What does ozone protect us from?2. What is molecular formula for ozone?3. Temperature stops increasing at -

stratopause

Atmospheric layers video

F. Mesosphere

1. 3rd layer 2. Temperature decreases as altitude

increases1. No gases that absorb the sun’s radiation.

3. Coldest layer ~ -80°C*

G. Thermosphere

1. Temperature increases as altitude increases1. Oxygen and nitrogen in this layer absorb sun’s

radiation

2. Hottest layer ~980°Ca. Convert to Farhenheit1) Tf = 32 + 9/5 Tc Tf = 32 + 9/5 (980) Tf = ? 1796° F

3. Outer portion= exosphere

H. Ionosphere

1. Electrically charged ions; solar radiation1. What is ion?2. Positively charged ion?

2. Upper mesosphere and lower thermosphere

3. Helpful in radio communication

II. Air Pressure1. Atmospheric pressure – pressure due to weight of

atmosphere2. 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.1. Mercury barometer

Air Pressure video

III. Human Influence on Atmosphere

1. Clorofluorocarbons (CFC’s) destroy ozone molecules.

1. Already a hole in ozone near south pole.2. Ozone is getting thinner.

2. Excess carbon dioxide leads to greenhouse effect

1. Transportation vehicles responsible for ½ of pollutants in air.

3. Sun’s radiation trapped – global warming1. What effect can global warming have on

environment?

Ozone video

1. Solar radiation2. Some radiation

is reflected by clouds

3. Pollution from cars and factories release carbon dioxide.

4. Heat is released towards atmosphere. Some escapes, some is trapped by greenhouse gases.

Review Video