Get out your notebooks for notes Bell Work Get out your notebooks for notes What do we mean when we talk about our atmosphere? How high up into the sky does the our atmosphere go? What is our atmosphere made up of?

Atmosphere - 1

What is The Atmosphere? Atmo (vapor or air) + sphere (orb) Layer of gases surrounding Earth Where weather occurs Essential for life Keeps Earth warm

Contents of our air: Argon 0.9% CO2 0.03% Other ~0.07% O2 21% Nitrogen 78%

Oxygen: All living organisms require Carbon Dioxide: Required for photosynthesis; keeps the Earth warm photosynthesis

Nitrogen: All living organisms need for proteins & DNA; the atmosphere is Earth’s nitrogen reservoir

Other components in the air: 1. Water Vapor Occurs as clouds. Absorbs solar energy.

2. Ozone Layer: Made up of O3 molecules 10-50 km above Earth Absorbs harmful UV radiation Without CO2 and ozone the average temperature on Earth would be -6o C

3. Atmospheric Solids Salt from sea spray and dust Condensation nuclei: form when dust & salt attract water vapor; leads to clouds, hail & snow formation

Heat on Earth comes from solar radiation that is … Absorbed by Earth Scattered back to Earth by CO2, H2O, and other gases in the air

Layers of the Atmosphere Characterized by distance from Earth & temperature Further from Earth, there are fewer molecules in the air – pressure ↓, the air is “thinner”

Troposphere To ~16 km high Temp. ↓ with distance above Earth Most weather happens here Most pollution is trapped here

Stratosphere From 16 - 50 km Most ozone is here Temp. ↑ with height because of ozone Very little water vapor

Mesosphere From 50-80km Temp. ↓ as you rise No Ozone Very thin air (few molecules)

Thermosphere Beyond 80 km Temp. ↑ with height (more solar rays absorbed) Air very thin – won’t feel hot Aurora occurs here

Aurora Borealis: Particles from the Suns solar winds interact with the magnetic field of the Earth to form the Aurora.