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CHM 412 Exam IV

Terms in this set (27)

Blackbody
An object that is 100% efficient in absorbing and emitting electromagnetic radiation
Blackbody radiation wavelength is dictated by...
Temperature
Earth
Also behaves like a blackbody
Absorbs 46% of the sun's energy and then radiates it back out
Clouds
Reflect 17% of the sun's radiation
Absorb 4%
Albedo
Earth reflecting the sun's radiation
6%
Primarily from surface waters
Windows to the atm
Wavelengths where greenhouse gases don't absorb
Radiation doesn't get trapped and can leave the atmosphere
To absorb IR...
The molecule must possess a dipole moment and during the vibration there must be a change in the magnitude of the dipole
Gases that do not absorb IR
1. Single atom (monoatomic)
Ar, O, N, He
2. Homonuclear diatomic molecules
N2, O2, Cl2
No dipole
Gases that DO absorb IR
1. Heteronuclear diatomic molecules
CO
2. Larger heteronuclear molecules
CO2
Residence time of H2O in atm
Only 10 days
Max mixing ratio of water is related to...
Temperature
Relative humidity
The air is holding X% of the amount that it could hold at a given temp
To find mixing ratio:
Rault's law to find P-H2O then divide by P-air (1 atm) --> %
Base period for greenhouse gas analyses
1951-1980
Keeling Curve
In Mauna Loa, HI since 1958
Collected data about greenhouse gases
Prior data obtained from gas pockets in ice cores
Why CO2 = primary gas of concern
We produce the most of it
CO2 absorbs IR strongly
Ranking greenhouse gases
1. Atmospheric concentration
2. Wavelengths at which the gas molecules absorb
3. Strength of absorption per molecule
Radiative Forcing
Measure the influence a gas has in altering the balance of incoming and outgoing energy in the atmosphere
Average additional energy (Watts/m^2) made available to Earth with increased mixing ratio of the gas
Relative Instantaneous Radiative Forcing (RIRF)
CO2 value = 1.0
All other gases compared to CO2
Positive Radiative Forcing
Absorbs IR radiation
Decrease in stratospheric O3
Cooling
Increase in tropospheric O3
Warming
Global Warming Potential
Includes atmospheric lifetime/residence time
CO2 has GWP = 1.0
CFCs have high RIRF
Stable b/c F molecules
Strong IR absorbers (absorb in the atmospheric "windows" = bad)
Also have long lifetime (high GWP)
Soil adsorption coefficient (Kd)
Concentration of chemical in soil/Concentration of chemical substance in water
Slope of Sorption Isotherm graph
Cs (mg/kg) / Cw (mg/L)
Kd = L/kg
Soil organic carbon-water partitioning coefficient (Koc)
the ratio of the mass of a chemical that is adsorbed in the soil per unit mass of organic carbon in the soil per the equilibrium chemical concentration in solution.
The "distribution coefficient" (Kd) normalized to total organic carbon content
n-octanol-water coefficient (Kow)
Concentration in Octanol/ Concentration in water
Values of Kow are unitless and usually expressed as logKow
Ozone hole typically forms in which month?
October
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