1. Greenhouse gases and global warming

The greenhouse effect is created by a difference in the way the Earth's atmosphere reacts to electromagnetic heat waves. A distinction must be made between short-wave radiation (CLO), i.e. ultraviolet and visible waves, and long-wave radiation (GLO), mainly infrared. Opaque bodies emit GLO-type heat waves, and generally absorb a large proportion of CLO and GLO waves. On the other hand, some gases and transparent solids let through a large proportion of GLO waves without absorbing them, but do absorb GLO waves.

The sun mainly emits GLO waves, a large proportion of which pass through the earth's atmosphere and are absorbed by the earth's surface (absorptivity around 90%). The earth, for its part, emits infrared heat waves, depending on its temperature, which are largely absorbed by the earth's atmosphere, which in turn emits GLO waves towards the earth (figure...