When autumn arrives, leaves fly, trees bend, and windows rattle. But why is this season often windier? Is it just an impression or a meteorological reality? To understand, we need to look up at the sky... and observe what's happening there.
Winds are born from contrasts
Wind is simply air in motion, caused by a pressure difference between two areas of the atmosphere. When there's an imbalance, air moves to restore equilibrium: it's this movement that we feel as wind.
Now, in autumn, these pressure differences become more frequent and more pronounced. Why? Because in summer, heat is relatively uniform between regions. But starting in September, the sun heats less intensely, and not in the same way everywhere. Some areas (oceans, large bodies of water) retain heat longer, while continents cool down faster.
Result: strong temperature contrasts... and therefore pressure contrasts!
The atmosphere becomes more "active"
With these contrasts, weather events multiply. Depressions (low-pressure areas) become more frequent, especially in temperate zones. These are what bring wind, rain, and sometimes storms.
In summer, high pressures dominate, which often blocks winds. In autumn, high pressures shift and disturbances from the Atlantic regain the upper hand. The famous "depression track" (or jet stream) also moves southward, bringing more turbulence with it.
In short, autumn is a season of rapid changes: warm air and cold air frequently meet... and wind is the messenger of this invisible confrontation in the sky.