Atmospheric Pressure and Winds — Question 9

Tropical cyclones-

1. Tropical cyclones are mainly developed over the sea.
2. They are usually limited to a small area and usually travel from east to west.
3. When there is a tropical cyclone the air is still, but the temperatures and the humidity are high. There is sudden drop in air pressure.
4. When the front of the vortex arrives, there are strong winds and thick clouds, then the winds become violent with great speed. Dense clouds and heavy rain reduce visibility.
5. The eye of the cyclone heralds a calm condition.
6. When the rear of the vortex arrives, there are violent winds, thick clouds and heavy rains. The wind blows in the opposite direction.

Temperate Cyclones-

1. Temperate cyclones are produced both on land and on sea.
2. They occupy areas measuring a couple of thousands of kilometres and move from west to east.
3. In a temperate cyclone, the wind speed is low.
4. All sectors of the cyclone have different temperatures.
5. There is not a single place where the winds and rains are inactive.
6. Direction of winds rapidly change at the front.
7. The approach of a temperate cyclone is marked by fall in temperature, fall in the mercury level, wind shifts and a halo around the sun and the moon.
8. A light drizzle follows which turns into a heavy downpour.
9. They cause light rainfall which continues for many days.