answer for part A. 1 The Greenhouse Shield a) Consider a planet, those atmospher

Question

answer for part A.

1 The Greenhouse Shield a) Consider a planet, those atmosphere is transparent in the solar spectral band and is a black body radiator in the thermal spectral band, thus having a emissivity of 1 The surface temperature shall be To, those of the atmosphere Ti and the equilibrium (radiation) temperature Te, which follows from T.What is the radiative equilibrium at the surface and for the whole system (surface and atmosphere)? Show in particular, that Compute the greenhouse effect G = To-Te for the planets Venus, Earth and Mars, using literature values for the solar constants and planetary albedos. (2 marks) b) Now the atmosphere is not "black" (emissivity 8

Explanation / Answer

(a)Planetary solar constant and albedo and densities

Venus = 2586 w/m2 ,   0.75 , 5.24 g/cm3

Earth = 1353 w/m2 , 0.30 , 5.51 g/cm3

Mars = 586 w/m2 , 0.25 , 3.93g/cm3

For Venus

Te4 = (S0 /4?)(1-ap)

      =(2586/4*5.24)(1-0.75)

Te =2.3566

To =2.802

G=T0 -Te =2.802-2.356= 0.446

For Earth

Te4 = (S0 /4?)(1-ap)

      =(1353/4*5.51)(1-0.3)

Te =2.56

To =3.04

G=T0 -Te =2.802-2.356= 0.484

For Mars

Te4 = (S0 /4?)(1-ap)

      =(586/4*3.93)(1-0.25)

Te =2.299

To =2.734

G=T0 -Te =2.802-2.356= 0.435

(b) T0 -Te =(1/(1- (emmisivity/2)))1/4

         33 4 = (1/1-(emmisivity/2))

1-(emmisivity/2) = 1/1185921

emmisivity/2=0.9999

emmisivity =0.499

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