Solar Constant and Solar Temperature

Solar Constant:

It is defined as the amount of radiant energy received per unit area by a perfectly black body placed on earth at the mean distance of the earth from the sun in a direction perpendicular to the direction of the rays from the sun. It’s value is nearly 1300 J.m-2.s-1 or 1300 W.m-2

Solar Temperature:

The central region of the sun is very hot. This region is called the photosphere which is surrounded by a comparatively cooler atmosphere called Chromosphere. For all external purposes, the temperature of the sun means the temperature of the chromosphere.