Wind
Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Class 7, Ch 2 "Understanding the Weather"; Class 9, Ch 3 "Atmosphere and Climate"
Meaning
Wind is air moving sideways across the Earth's surface, from areas of high pressure to areas of low pressure. It has a speed and a direction. A wind is named after the direction it comes from, so a westerly blows from the west. Three forces shape it: the pressure gradient force starts it, the Coriolis force (from the Earth's spin) bends it, and friction from the ground slows it. Winds carry heat and moisture around the world.
Example
The loo is a hot, dry westerly wind. It blows across the north-west plains of India in May and June. It comes from the west, so it is called a westerly.
Don't confuse with
- Air currents: these are mostly up-and-down movements of air, as in rising warm air. Wind refers to horizontal movement.