why is the atmospheric temperature very low at higher altiotudes ?

Answer 1

The atmosphere absorbs more heat from the earth than the sun, because it is nearly transparent in the solar spectral regions. At higher altitudes the earth radiation does not heat as much because the the air at lower altitudes has already absorbed the radiation.

Answer 2

Check this link for your answer its pretty detailed.


http://en.wikipedia.org/wiki/Atmospheric#Temperature_and_the_atmospheric_layers