L12.1

L12.1 - -Contains almost all ozone in atmosphere-Ozone...

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11/12/09 Earth’s Atmosphere Composition: - 78% N2 – out gassing - 21% O2 – photosynthesis - ~1% Other (H2O, CO2, etc) Effect on Life: - O2 to breathe - Warms Earth (greenhouse effect) - Distributes heat - Shields us from harmful radiation (X-rays, UV, solar wind) - Distributes H2O - Scatters light Global Winds – circulation Convection – heats air at Equator, rises, transported to Poles (Hadley Cells) Coriolis Effect – deflects motion in rotating systems from straight paths to circular ones Circulation Cells – Coriolis Effect acts on Hadley Cells diverts N-S convection to E-W divides larger cells into 3 small ones per hemisphere creates easterly trade winds, temperate westerlies, and polar easterlies Layers of Atmosphere: 1) Troposphere (up to ~15 km) - Highest density contains vast majority of all air in atmosphere - Where weather happens, greenhouse effect works - Temperature drops as altitude increases 2) Stratosphere (up to ~60 km)
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Unformatted text preview: -Contains almost all ozone in atmosphere-Ozone Layer Ozone (O3) UV radiation hits O3 molecule and dissociates it into O2 + O and gives off energy/heat O3 + UV O2 + O + E (heat) Increase in altitude, gets warmer (UV more likely to react with O3)-Due to hotter air, no convection (cooler air cant rise)-Chemicals stay there for decades 2) Mesosphere (up to ~90 km)-Temperature drops with higher altitude-Last relatively dense layer of atmosphere-Where most meteors burn up 3) Thermosphere (90 250/500 km changes)-X-ray and UV radiation heat up layer (as high as 2500 C)-Radiation ionizes molecules, produces ionosphere layer of ions which reflect radio waves from surface-Can have radios, cell phones, etc 4) Exosphere-Outermost layer, extremely thin-Air molecules heated up by X-rays and UV escapes atmosphere...
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