|
Torrential rain causing flooding in England in the middle of July, particularly clement winters across Europe … Certain experts believe that these climatic changes are linked to an exacerbation of the greenhouse effect. But what is the greenhouse effect ?
The term « greenhouse effect » has been adopted by analogy with what is observed in the glass or plastic greenhouses used by horticulturists. In fact, part of the solar energy accumulated in a greenhouse during the day remains trapped behind the glass or plastic, in the water vapour, and results in an increase in temperature (see picture 1).
In the same way, on the Earth’s surface, there is a natural greenhouse effect, due to the presence in the atmosphere of «greenhouse gases» (GHG). These gases behave in the same way as the water vapour in a greenhouse : they play a role in retaining the heat on the Earth’s surface (see picture 2).
This natural greenhouse effect is one of the necessary conditions for the presence of the biosphere1, as we know it on the surface of the Earth.
1 « Envelope » consisting of all the beings living on the Earth’s surface. |