# Surface temperature of the Earth

This looks to be a fairly straightforward problem. I'm not sure why I'm having trouble.

The radiant energy flux density is the energy emission per unit area. Why would I not simply multiply the solar constant of the Earth times the surface area of the Earth? Of course, it would be a plane area approximation. Then, whatever that energy emission value that is, set it equal to the Stefan-Boltzmann constant*(TE)4*4pi*(RE)2?

Is the radiant energy flux density multiplied by the area equal to the power?

http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110318_204153.jpg?t=1300499036 [Broken]

Last edited by a moderator:

The cross section of the earth you would use is not its surface area. It will be Pi*R^2. It is the area of the shadow that the earth would cast on a plane perpendicular to the sun's intensity vectors.

The cross section of the earth you would use is not its surface area. It will be Pi*R^2. It is the area of the shadow that the earth would cast on a plane perpendicular to the sun's intensity vectors.

Sorry, I was ambiguous. I meant plane area approximation, not surface area.

How do you calculate the radiant energy flux density at the Earth in terms of the Sun's temperature?

The manual has

JE = sigmaB*(TS)4*[(RS)/(DE)]2

I'm not quite sure why they multiplied it by the tangent squared.

Why did they multiply it by [(RS)/(DE)]2?