ESS55
Prof. Jin-Yi Yu
Planetary Energy Balance
§
Energy emitted by Earth
= Energy absorbed by Earth
s
T
e
4
x
(4
p
R
2
Earth
)
=
S
p
R
2
Earth
x
(1-A)
s
T
e
4
=
S/4 * (1-A)
= 1370/4 W/m
2
* (1-A)
=
342.5
W/m
2
* (1-A)
=
240
W/m
2
§
Earth’s
blackbody
temperature
T
e
= 255 K (-18
°
C)
Earth’s
surface
temperature
T
S
= 288 K (15
°
C)
greenhouse effect (33C) !!
(from
Global Physical Climatology
)