1
Radiative--Moist Convective
Radiative
Equ
quilib
ilib
ilibrrium
2
Precipitating Convection favors Widely
S
Spaced
d Cl
Clouds
d (Bj
(Bjerknes,
k
1938)
3
Properties:
• Convective updrafts widely spaced
• Surface enthalpy flux equal to vertically
integrated radiative cooling
c pT wT
M
Q
•
T wz
• Precipitation = Evaporation = Radiative
Cooling
• Radiation and convection highly interactive
4
Manabe and Strickler 1964 calculation:
5
Approach to Radiative
Radiative--Convective Equilibrium: Precipitation
5
4.5
Precip
pitation (mm
m /day)
4
3.5
3
2.5
2
1.5
1
0.5
0
1
2
3
4
5
6
Time (days)
6
7
8
9
10
Approach to RadiativeRadiative-Convective Equilibrium: T and q
7
8
9
10
11
12
13
14
Recovery from mid-level specific humidity
perturbation
t b ti
Specific humidity perturbation (g/Kg), from -5.479 to 2.645
-100
-200
-300
P (m
mb)
-400
-500
-600
-700
-800
-900
-1000
1
2
3
4
5
6
Time (days)
15
7
8
9
10
MIT OpenCourseWare
http://ocw.mit.edu
Spring 20
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16