1. The Atmosphere 1. functions 2. composition 3. layers

2. Vital Functions: Protection from impact of meteors Protection from impact of meteors Protection from cosmic radiation Protection from cosmic radiation Protection from temperature extremes Protection from temperature extremes Supplies oxygen and carbon dioxide Supplies oxygen and carbon dioxide Makes hydrologic cycle possible Makes hydrologic cycle possible

3. Composition: a mechanical mixture

5. Vertical structure of atmosphere Atmosphere has mass Atmosphere has mass top of atmosphere = 300 miles top of atmosphere = 300 miles half atmosphere’s mass is below 3.5 miles half atmosphere’s mass is below 3.5 miles

6. Atmospheric pressure: force per unit area normal atmospheric pressure at sea level : 14.7 lb/sq. in 1013 mb 760 mm Hg (29.9in Hg)

8. Temperature Layers Temperature Layers

9. a) TROPOSPHERE: (from surface to 11 miles) temp decreases with altitude temp decreases with altitude at an average rate (“normal lapse rate”) 3.5 o F/1000ft (6.4 o C/km) at an average rate (“normal lapse rate”) 3.5 o F/1000ft (6.4 o C/km) 90% mass 90% mass weather,water vapor, clouds weather,water vapor, clouds turbulent, mixed turbulent, mixed thickness varies with latitude thickness varies with latitude Tropopause: top; temp stops decreasing elevation varies with latitude elevation varies with latitude

10. temp decreases with altitude at an average rate (“normal lapse rate”) 3.5 o F/1000ft (6.4 o C/km)

11. a) STRATOSPHERE : from tropopause to 31 miles from tropopause to 31 miles stratified stratified ozone ozone temperature increases with altitude temperature increases with altitude Stratopause: temp. stops increasing with altitude

12. c) MESOSPHERE: 31 to 50 miles 31 to 50 miles single-atom oxygen single-atom oxygen noctilucent clouds noctilucent clouds temp. decreases with altitude temp. decreases with altitude shooting stars shooting stars Mesopause: lowest temp -130 o F

16. d) THERMOSPHERE: > 50 miles > 50 miles highest temps in atmosphere (up to 2000 o F) highest temps in atmosphere (up to 2000 o F) Beyond 300 miles: vacuum Beyond 300 miles: vacuum