Enviroweb HomeAtmosphere Contents
4. Energy Budgets
The solar constant is the amount of solar radiation which reaches the outer atmosphere
Click to view larger version
For scientific convenience the active surface may be considered as a black body (a perfect absorber of radiation). In reality everything on the Earth behaves as if it is grey. For many practical purposes, scientists assume that the sun emits energy like a black body at a temperature of approximately 6000ºC. This assumption allows scientists to model the spectral distribution and amount of solar radiation in the visible spectrum which reaches the outer atmosphere of the Earth. For example, black body laws predict that 1365 watts per square metre will reach the outer atmosphere. The next slide gives an example calculation to work out the Earth's surface temperature using the above assumptions.
What is the solar constant?