Atmospheric Structure and Composition. Atmosphere: The thin envelope of gases surrounding the earth...
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Transcript of Atmospheric Structure and Composition. Atmosphere: The thin envelope of gases surrounding the earth...
Atmospheric Structure Atmospheric Structure and Compositionand Composition
Atmosphere: The thin envelope of gases surrounding the earth
Highly compressible
Density decreases rapidly with height
Air: A mechanical mixture of gases and aerosols
DefinitionsDefinitions
Vertical Structure of AtmosphereVertical Structure of Atmosphere
Troposphere (surface to 8-20 km)
Upper boundary varies from about 8 km (poles in winter) to about 20 km (tropics)
Weather and climate layer
Most of atmosphere’s mass; all of its water
Vertical Structure of AtmosphereVertical Structure of Atmosphere Troposphere (surface to about 8-20 km)
Upper boundary varies from about 8 km (poles in winter) to about 20 km (tropics)
Weather and climate layerMost of atmosphere’s mass; all of its
water
Stratosphere (8-20 km up to about 50 km)
Ozone (O3) LayerTemperature inversion
Vertical Structure (ctd.)Vertical Structure (ctd.)
Mesosphere (50-80 km)– Temperature decreases with height. Why?
Thermosphere (80-? km)– Temperature inversion. Why?
Vertical Structure (ctd.)Vertical Structure (ctd.) Homosphere vs. Heterosphere
Vertical Structure (ctd.)Vertical Structure (ctd.) Homosphere vs. Heterosphere
Transition zones between layers– Tropopause– Stratopause– Mesopause
Defining Layers by Function – Defining Layers by Function – the Ozonospherethe Ozonosphere
Roughly corresponds to the stratosphere
How does the ozone layer work?
Why is there a “hole” in the ozone layer?
– Why no “hole” where the pollution is produced?
Defining Layers by Function – Defining Layers by Function – the Ionospherethe Ionosphere
Upper mesosphere + thermosphere Produces the aurora borealis and aurora
australis D Layer – absorbs AM radio waves;
disappears at night E Layer – weakens at night F Layer – reflects AM radio waves
Composition of the AirComposition of the Air Uniform gases
Nitrogen (N2) 78%, (O2) 21%,
Argon (Ar) 1%, trace gases (Neon, Helium, Methane (CH4), etc.)
Variable gases
Water Vapor (H2Ov), O3, CO2
Composition (ctd.)Composition (ctd.) Aerosols
Solid: Ice/salt crystals, soil particles, volcanic dust
Condensation nuclei
Liquid: Water droplets (cloud, fog)
Origin of the AtmosphereOrigin of the Atmosphere Volcanoes release H2, CO2, H2Ov, N2, NH3, CH4
No O2 or O3, so no land organisms!
One-celled aquatic organisms release CO2 to atmosphere when breaking down food through fermentation
Simple aquatic plants took in CO2 and released O2 to atmosphere via photosynthesis
O3 formed from the O2
Origin of Atmosphere (ctd)Origin of Atmosphere (ctd)
CO2 gets stored in shells and decaying plants
N2 builds up in atmosphere