Wind and Air Pressure

How Wind is Formed

Air always moves from a region of High Pressure to a region of Low Pressure. This moving air is called Wind.

The Mechanism

1. Uneven Heating: The Sun heats the Earth unevenly (e.g., Equator gets hotter than Poles; Land heats faster than Sea).
2. Warm Air Rises: When air heats up, it expands, becomes lighter, and rises.
3. Low Pressure Created: The rising warm air leaves behind a gap (Low Pressure area).
4. Cool Air Rushes In: Cool, dense air from a surrounding High Pressure area rushes in to fill the gap.
5. Wind: This movement is what we feel as wind.

High-Speed Winds and Reduced Pressure

There is a fascinating rule in physics (related to Bernoulli’s principle):

High-speed winds are accompanied by reduced air pressure.

Activity: Blowing between Balloons

If you hang two balloons close together and blow air forcefully between them, they move towards each other.

• Why? Blowing increases air speed between them $\rightarrow$ Pressure decreases between them.
• The higher pressure outside the balloons pushes them inwards.

Blowing Off Roofs

During a storm, high-speed winds blow over the roof of a house.

1. Above Roof: High speed wind $\rightarrow$ Low Pressure.
2. Inside House: Still air $\rightarrow$ High Pressure.
3. Result: The high pressure inside pushes the roof upwards, blowing it away.