Effects of Solar Radiation on the Earth

A number of factors affect the amount of 
solar radiation that reaches a particular 
surface., these include the length of day, 

the angle of incidence of sunlight on the ground at
each time of day, and the amount of atmosphere traversed by the
radiation at each time of day. 
Of these three, atmospheric interference
is the most difficult factor to evaluate. 
Solar intensity just outside the earth's atmosphere 
is about 130 watts per square foot (1,400 watts/m2). 
At an altitude of about 15 miles, a stratum of ozone
and nascent oxygen absorbs most of the ultraviolet 
portion of the solar waves.
In the lower reaches of the atmosphere, carbon dioxide,
water vapor, clouds, dust, and pollutants work in 
various ways to reflect, scatter, absorb, and reradiate 
different parts of the spectrum.
The shorter wavelengths of sunlight, which are the
 most affected, produce the blue appearance of 
the daytime sky. 
A considerable portion of the sunlight's energy is 
stripped away  by the "clear" atmosphere—nearly 
half, on the average, worldwide. 
Most of this energy is then reradiated from the 
atmosphere into space, but a significant amount is 
reradiated from the atmosphere to the earth as
diffuse sky radiation, thus slightly increasing the 
total amount of solar