Chapter 19: Earth’s Atmosphere
What is in our atmosphere? 78% N2 Cycle, nitrogen-fixed by bacteria in soil to roots, returned via waste & decay 21% O2 Cycle, used by respiration, fires, weathering, returned by photosynthesis Ozone: O3, absorbs harmful UV radiation, damaged by CFCs & exhaust 1% Ar & other Particulates: tiny solid or liquid from volcanoes, sea spray, pollen What is in our atmosphere?
Weight of atmosphere pressing down on Earth air pressure Pressure decreases w/ altitude Pressure increases as temperature increases Pressure decreases as humidity increases b/c water vapor is less dense than air Measured w / barometer (atm., mm, mb) Atmospheric Pressure
Measuring Air Pressure Mercurial Aneroid Measuring Air Pressure
Layers of the Atmosphere Temperature patterns mark layers As Altitudes increases, Pressure decreases Layers of the Atmosphere
Layers of the Atmosphere Troposphere At surface, weather, almost ½ of all H2O & CO2 Altitude increases, Temperature decreases Ends in Tropopause (12 km) Stratosphere Contains OZONE LAYER As altitude increases, temperature increases b/c absorbing sun’s energy (UV) Ends in Stratopause Layers of the Atmosphere
Layers of the Atmosphere cont. Mesosphere Temperature decreases as altitude increases Coldest temperature Ends with Mesopause Thermosphere Highest temperatures b/c of radiation, O2 & N2 absorbing sun’s energy Contains IONOSPHERE (Auroras) Exosphere: entrance into space Layers of the Atmosphere cont.
How does the sun’s energy affect OUR atmosphere? Electromagnetic Radiation Energy from sun, travels through space @ 3 x 10 m/s Earth heated by energy transfer 8 How does the sun’s energy affect OUR atmosphere?
Electromagnetic Radiation LONGER WAVELENGTHS/LOWER ENERGY SHORTER WAVELENGTHS/HIGHER ENERGY Electromagnetic Radiation
Upper Atmosphere (U.A.) absorbs almost all radiation except some visible & infrared reach surface SCATTERING: L.A. deflects radiation in all directions Absorbed radiation heats surface & emitted as infrared
What’s reflected is “ALBEDO”