Upload
cora-briggs
View
219
Download
0
Embed Size (px)
DESCRIPTION
Atmospheric Composition today
Citation preview
Structure of the Earth’s Atmosphere
* Chemical Composition* Vertical Layers* Coriolis Force* Hadley Cells
Current Composition
Atmospheric Composition today
Troposphere Surface layer - 30,000 ft Heated from below General T structure dec. w/height Convection - weather, clouds form from rising air
which cools by pressure drop, and clouds dissipate as air falls and heats.
Stratosphere Heated by ozone absorbing UV light
UV breaks apart ozone into O2 + atomic oxygen - get energy release and heating.
higher altitudes efficiently absorbs UV at 200 and 350 nm. lower altitudes less efficiently absorbs UV at 44 and 80
nm
Temperature inversion - no convection, no weather.
7 – 30 miles
MesosphereMass of atmosphere 0.1% Density is too low for ozone chemistry
to heat get normal trend we saw in
troposphere– lower T with inc. altitude. 30-50 miles
Ionosphere (= Thermosphere) Density so low Space Shuttle orbits
here, with little drag T can be very high; 4,000F.
But no significant heat because density low.
Heated by ionization by UV from the sun, and the solar wind.
Hadley Cells
Hadley, Ferrel, Polar Cells
Earth’s atmosphere divides into 3 cells. Coriolis deflection sets the major constraint on
how many cells the atmosphere of a planet divides into. stronger for more rapid rotation. size of the planet and speed of rotation which determines number of cells
Hadley Cell Solar heating at equator is strongest - causing
rising convective air which is pushed north and south at the tropopause
At ~30deg latitude deflected enough by Coriolis force to be moving almost due east.
Meets air moving down from the north (Ferrel Cell air) and both descend, warming and drying
Trade Winds - return of surface wind to equator
Coriolis Effect 6 min YouTube (start 1min in for merry-go-
round demo)