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12.842 / 12.301 Past and Present Climate
Fall 2008
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Flux of water by convection makes real problem complex
Image courtesy of NASA.
Frequency histogram of rawindsonde relative humidities from 1600
ascents at the tropical Pacific islands of Yap, Koror, Ponape and Majuro, January-May, 1994-95. Spencer and Braswell, Bull. Amer. Metor. Soc.,
1997.
Image courtesy of AMS.
(a) Sigma_s
Sensitivity of relative humidity to
assumptions about cloud
microphysical processes
(b) Sigma_d
(c) Terminal velocity of rain
(d) Terminal velocity of snow
0
(e) Rain evaporation coefficient
100
(f) Snow evaporation coefficient
200
300
400
Pressure (mb) 500
600
700
800
900
1000
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
Sensitivity to microphysics increases with vertical resolution of model
rh sensitivity (25 mb)
rh sensitivity (100 mb)
0
100
200
300
400
500
600
700
800
900
1000
-0.09 -0.08 -0.07 -0.06 -0.05 -0.04 -0.03 -0.02 -0.01
Relative humidity difference (%)
0
0.01
Observed RH
Predicted RH
0
100
200
300
400
Pressure (mb) 500
600
700
800
900
1000
0
0.2
0.4
0.6
0.8
1
1.2
Effects of Clouds on Radiative Transfer
• Responsible for much of Earth’s albedo
• Important greenhouse effect from
longwave absorption and re-emission
Figures removed due to copyright restrictions.
See Figures 3.13, 3.14, 3.15, etc. in Hartmann Dennis L. Global Physical Climatology. Reading, MA: Academic Press, p. 411. ISBN: 0123285305.