Summarize the following text in French (in 10 lines at most).

GLOBAL AND LOCAL WIND SYSTEMS

The earth's wind systems are air masses that are moving around as a result of variations in air pressure. 
The variations in air pressure are due to differences in solar heating over the earth.
Think of a solar panel : it absorbs much more of the sun's energy when it is positioned so that the 
collection surface is perpendicular to the sun's rays than if it is positioned at an oblique angle to the 
rays. Similarly, one square metre of the earth's surface on or near the equator receives more solar
radiation per year than one square metre at higher latitudes. (The curvature of the earth means that its 
surface becomes more oblique to the sun's rays with increasing latitude.) As a result, the tropics are
considerably warmer than our regions.

Like all gases, air expands, or increases in volume, when heated, and contracts, or decreases in volume, 
when cooled. In the atmosphere, warm air is lighter and less dense than cold air and will rise to high
altitudes when strongly heated by solar heating of the earth. Warmer air near the equator will flow upward
and then outward towards the poles where the air near the surface is cooler. The regions of the earth near
the poles then have more air "pressing down" on them, and the cooler surface air tends to slide away from
these areas and move towards the equator.

In addition to the main global wind systems there are also local wind patterns, e.g., sea breezes. Sea
breezes are generated in coastal areas as a result of the different heat capacities of sea and land, wich
result in different rates of heating and cooling. The land has a lower heat capacity than the sea and thus
heats up quickly during the day, but at night it cools down more quickly than the sea. During the day, 
the sea is therefore cooler than the land and this causes the cooler air to flow towards the shore to 
replace the rising warm air on the land. During the night the direction of flow is reversed.


Source : Renewable Energy (Edited by G. Boyle) Oxford University Press.