2. Cont’d
The Sun releases an estimated 384.6 yotta watts (3.846×1026 watts) of energy in the form
of light and other forms of radiation.
As viewed from earth, the radiation coming from the sun appears to be equivalent to that
black surface at 5762° K .
The rate at which solar energy arrives at the top of the atmosphere is called the SOLAR
CONSTANT,
3. The distance between the sun and earth varies through out the year.
This can be approximated by the equation
Where n = day of the year
Spectral distribution of solar intensity → to know the percentage of radiation obtained at
certain wave length
𝐼
𝐼𝑠𝑐
= 1 + 0.033cos
360(𝑛 − 2
365
