The Sun-Earth relationship.

The Earth's atmosphere evolution through geological comes has induced signi ficant changes in its composition. The properties of today's atmosphere, du e in particular to the presence of oxygen, show strong evidence of the Sun- Earth relationship. The influence of solar activity will be presented, conc erning the neutral and ionised atmosphere including the magnetosphere, the thermosphere down to the troposphere, and climate as well as the various co nsequences on our environment (space weather). (C) 2001 Academic des scienc es / Editions scientifiques et medicates Elsevier SAS.