re: #579 woodentop

It acts as a buffer.

Not a very good answer.

“buffer” is used in computer science and chemistry with their very specific meanings.

The atmosphere of Earth acts both as an optical medium and as a kinetic (thermal) energy transport.

If you or anyone else with sufficient (1st year college physics) background are interested in more detail, Professor Ray Pierrehumbert at the Univ. of Chicago has finally completed his freely available textbook on an introduction to climate physics (atmosphere):

The Climate Book

Or of course you could pay the $70+ for a regular college level text.