Atmospheric Structure . Theodore S. Dibble Chemistry Department SUNY-Environmental Science and Forestry Syracuse, NY. Temperature defines regions of the atmosphere. Pressure (mbar). Altitude (km). Pressure and the Barometric Law.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Theodore S. Dibble
SUNY-Environmental Science and Forestry Syracuse, NY
P = Poe-Mgh/RTapplies to individual compounds at equilibrium
Atmosphere not at equilbrium!
Below 130 km, long lived gases have constant mole fraction
Pressure behaves as if M =28.8 g/mole (78:21:1 N2:O2:Ar)
Exercise: Calculate the partial pressure of
O2 at 6 km if PTotal is 0.5 bar.
How can chemistry (reactions) occur?
Part per million, etc. by volume = mole fraction
1 ppmv = mole fraction 1 x 10-6
1 ppbv = mole fraction 1 x 10-9
1 pptv = mole fraction 1 x 10-12
Molecules/cm3 (use ideal gas law)
1 atm = 2.5 x 1019 molecules cm-3 at 298 K
if PTotal = 1 atm, 1 ppmv = 2.5 x 1013 molecules cm-3
PTotal = 1 Torr 3.2 x 1016 molecules cm-3
At 220 K, 1 Torr = 4.3 x 1016 molecules cm-3
Mixing Times in Troposphere
ground to tropopause in 1 week
Around a latitude line in weeks
Mid-latitude to equator in months
Cross equator in 1 year
[CO] = 120 ppbv in N.H. and 60 ppbv in S.H.
Question: CO has a lifetime of ~2 months
Will it be evenly distributed over oceans and remote continental regions within the N.H.?