4.4 - Atmosphere

Question 1

Gases of the Earth’s atmosphere

Answer 1

1. 78% - Nitrogen: Mostly in the form of N2 (unuseable to plants without being fixed)
2. 21% - Oxygen: Produced by photosynthesis in plants & needed for human/animal respiration
3. 0-4% - Water Vapor: Varies by region & conditions; acts as a temporary GHG, but less concerning than CO2 (Quickly cycles through atmosphere)
4. .93% - Argon: Inert, noble gas
5. .04% - CO2: Most important GHG; leads to global warming. Removed from atmosphere by photosynthesis

Question 2

Layers and characteristics of the earth’s atmosphere (kinda long…)

Answer 2

1. troposphere
   - tropo = change (weather occurs here)
   - 0-16km
   - most dense due to pressure of other layers above it
   - Most of the atmosphere’s gas molecules are found here
   - Ozone (O3) in the troposphere is harmful to humans (respiratory irritant) and damages plant
   stomata, and forms smog
2. Stratosphere
   - “S” for second
   - 16-60km
   - less dense due to less pressure from layers above
   - Thickes O3 layer is found here; absorbs UV-B and UV-C rays, which can mutate the DNA of
   animals (cancer)
3. Mesosphere
   - Meso = Middle
   - 60-80km
   - even less dense
4. Thermosphere
   - Therm = hottest temp
   - absorbs harmful X-rays and UV radiation
   - charged gas molecules glow under intense solar radiation producing northern lights
5. Exosphere
   - outermost layer where atmosphere merges with space

Question 3

Temperature gradient of the earth’s atmospheric layers

Answer 3

1. Troposphere - temperature decreases as the air gets further from the warmth of the earth’s surface
2. Stratosphere - temperature increases because the top layer of the stratosphere is warmed by UV rays (like a pool’s surface)
3. Mesosphere - temperature decreases because density decreases, leaving fewer molecules to absorb sun (coldest place on earth -150°F)
4. Thermosphere - temperature increases due to absorption of highly energetic solar radiation (the hottest place on earth: 3,100°F)
5. Exosphere - no temperature because it merges with space

Question 4

Temperature gradient

Answer 4

layers of earth’s atmosphere are based on where temperature gradients change with distance form earth’s surface