Question

The intensity of sunlight at the earth surface is about 1000wlm2. The average temperature of the earth is about 58°

f. What must be the emissivity of the earth be?

Answer 1

The emissivity of the earth is 0.5

The emissivity of the earth is calculated by the Stefan's law

`q= sigma a curlyepsilon T^(4)1000=5.67*10^(-8)*4 pi *(6400*10^(3))^(2)* curlyepsilon *288^(4) curlyepsilon =0.5`