1. Environmental Chemistry

2. Atmospheric concentrations
Atmospheric Pressure:
1 atm = 760 torr = Pa = bar = mbar
Atmospheric abundances can be measured in pressure or “number density” (# molecules/volume):
𝑃 𝑅𝑇 = 𝑛 𝑉 moles/volume = molar concentration (moles/L)
𝑃 𝑁 𝐴 𝑅𝑇 = 𝑛 𝑁 𝐴 𝑉 # molecules/volume = number concentration or number density (molecules cm-3)
Mole fraction or “mixing ratio”:
𝑋 𝑖 = 𝑃 𝑖 𝑃 𝑡𝑜𝑡𝑎𝑙 = 𝑁 𝑖 𝑉 𝑁 𝑡𝑜𝑡𝑎𝑙 𝑉 (mole fraction is unitless!)
To convert mole fraction to ppmv (or ppbv, etc.):
ppmv = 𝑋 𝑖 × 106
ppbv = 𝑋 𝑖 × 109
pptv = 𝑋 𝑖 × 1012

3. Miniscule concentrations
Parts Per Million (PPMV)
A unit of concentration often used when measuring levels of pollutants in air, water, body fluids, etc. One ppm is 1 part in 1,000,000. The common unit mg/liter is equal to ppm. Four drops of ink in a 55-gallon barrel of water would produce an "ink concentration" of 1 ppm.
Parts Per Billion (PPBV)
One part per billion is 1 part in 1,000,000,000. One drop of ink in one of the largest tanker trucks used to haul gasoline would represent 1 ppb.
Parts Per Trillion (PPTV)
A unit of concentration used to measure vanishingly small levels of pollutants or contaminants. One ppt is 1 part in 1,000,000,000,000. One drop of ink distributed through the water contained in a 12-million-gallon reservoir would result in a final concentration of 1 ppt.

4. Brasseur, Orlando, and Tyndall, Atmospheric chemistry and global change, 1999.

5. Lifetime and variability
Hobbs, IAC, 2000.

7. Blackbody Radiation

8. Intercepted solar radiation
Jacob, Intro to Atmospheric Chemistry, 1999

9. Solar irradiance spectrum
Graedel and Crutzen, Atmospheric Change, 1993

10. Absorption and Reflection of Radiation

11. Albedo

12. Solar and terrestrial blackbody spectra

13. Solar and terrestrial blackbody spectra

14. Outgoing long-wave radiation

15. Terrestrial radiation spectrum
290 K
Jacob, Intro to Atmospheric Chemistry, 1999

17. IR spectrum of CO2

18. IR spectrum of H2O
bending modes
stretching modes

19. Typical IR absorption frequencies

20. Absorption by atmospheric gases
atmospheric window
5 μm