Chapter 11, Section 1 The Atmosphere

1.Importance of the atmosphere a. Def – thin layer of air that forms protective covering around the planet b. With no atmosphere, days would be extremely hot and nights would be cold c. Atmosphere protects life from sun ’ s harmful rays 1.Harmful rays are called ultraviolet radiation

What would Earth be like without an atmosphere? Extreme Temps No sound UV Radiation

2. Makeup of Atmosphere a. Gases 1.78% of atmosphere is Nitrogen 2.21% of atmosphere is Oxygen 3.1% is water vapor, carbon dioxide, trace gases like argon b. Solids & liquids 1.Solids include dust, salt, pollution, ash, pollen 2.Liquids include water vapor

a. Troposphere 1.Weather layer 2.We live in this layer 3.Water vapor & carbon dioxide are important gases for weather conditions 4. As altitude increases, air pressure decreases & temperature decreases 1.Altitude sickness – humans feeling ill due to the effects of lowered air pressure at increased altitudes Roll Presentation Express

3. Layers of the Atmosphere Temperature

a. Troposphere (continued) Lowest layer of Earth ’ s atmosphere Lowest layer of Earth ’ s atmosphere –Our weather layer –increase altitude –Tropo= change in Greek –Sphere = ball –Contains mass of atmosphere –Gets coolers as you increase altitude

b.Stratosphere 1.Strato = spreading out (Gk) 2.Sphere = ball (Gk) 3.2 nd layer from the ground 4.Contains ozone (O 3 ) layer 5.Cold until you reach the ozone layer at top of layer 6.Ozone layer is WARM

c.Mesosphere 1. 3 rd layer from the ground 2. Meso = middle (Gk) 3. Sphere = ball (Gk) 4. Coldest layer 5. Most meteors burn up in the mesosphere

d. Thermosphere 1. Hottest layer 2. Thermo = Heat (Gk) 3. Sphere = ball (Gk) 4. Satellites & shuttles in orbit 5. Air is extremely thin 6. Ionosphere -- layer of electrically charged particles –Auroras

Amazing Auroras

d. Thermosphere (continued)

e. Exosphere 1. Exo = outside (Gk) 2. Sphere = ball (Gk) 3. Exits to deep space 4. Receives sun ’ s radiation first

4. Atmospheric Pressure Most Pressure Least Pressure Gravity pushing down

4. Atmospheric Pressure a. Earth ’ s gravity pulls air molecules toward Earth 1.Molecules nearer Earth ’ s surface are closer together and therefore denser 2.This dense air exerts more force on an area. Force on an area is pressure.

5. Temperature in Atmospheric Layers a. Sun is source of most of energy on Earth & must pass through atmosphere to reach the planet a.Troposphere is heated by sunlight passing through and reflecting off Earth ’ s surface b.Stratosphere is cold except at the top where ozone is c.Mesosphere is coldest layer d.Thermosphere is hottest layer e.Thermosphere & exosphere receive sun ’ s rays first but there are few molecules of air

6. Ozone Layer a. Located in stratosphere b. Three bonded oxygen molecules c. Shields life on earth from harmful ultraviolet radiation 1.UV is one of many types of energy that comes to Earth from sun 2.UV can cause sunburns and skin cancer d. Chlorofluorocarbons are chemical compounds that may destroy the ozone layer 1.Many countries have banned CFC ’ s, which were found in refrigerators, aerosol cans, and air conditioners e. An ozone hole appears over Antarctica from August -- October