Abstract
Clouds have a major influence on climate balance. On the one hand, they reflect part of the sun's radiation back into space ; on the other, they contribute to the greenhouse effect. These two processes have broad but opposing impacts on the Earth's energy balance, and therefore partially offset each other. But the impact of clouds is very different, depending on whether they are thin, high clouds (cirrus clouds) or optically thick, low clouds (stratocumulus clouds). In the context of ongoing climate change, the evolution of clouds (frequency, altitude, thickness...) has the potential to reduce or increase warming due mainly to greenhouse gases. This is one of the main sources of uncertainty regarding the magnitude of climate change.
