Brief notes and some important questions on Winds

The horizontal movement of air is called wind. The movement is caused by the difference in air pressure.

Permanent Pressure belts:

There are some permanent pressure belts or zones in the world which are as follows.

Equatorial low-pressure belts:

In the equatorial regj_0r between 5°N and 5°S latitudes, the temperature is high throughout the year. The atmospheric pressure in this area is always low. This pressure belt is also known as doldrums. The calm and baffling winds in this region makes sailing difficult.

Polar high-pressure belts:

The Polar Regions are extremely cold throughout the year. In these regions the atmospheric pressure is high.

Sub-tropical high pressure belts:

Around 30°N and 30°S latitudes the air streams creates belts of high pressure in these two regions. These high pressure regions are known as the sub-tropical high pressure belts or horse latitudes.

Sub-polar low pressure belts:

The cold winds blowing” from the polar high pressure belts and warm winds blowing from the sub­tropical high pressure belts meet around the 60° latitudes in’ both the hemispheres and give rise to low pressure. These two regions are called sub-polar low pressure belts.

Permanent winds:

The winds arising due to the permanent pressure belts are called permanent winds. There are three permanent winds blowing from high pressure to low pressure belts. They are the trade winds, the westerly and the polar winds.

Trade winds:

The winds blowing from the sub-tropical high pressure belts to the equatorial low-pressure belts is called trade winds.

Westerlies:

The winds blowing from the sub-tropical high pressure belts to the sub-polar low-pressure belts is called westerlies.

Polar winds:

These winds blow in the frigid zones from the polar high pressure belts to the sub-polar low-pressure belts. They are also known as the polar easterlies.

Roaring Forties:

In southern hemisphere near 40° latitude the brave west blowing wind is called the Roaring Forties.

Cyclones:

A cyclone is an area of low pressure with strong winds, about the centre.

Monsoon:

Seasonal wind which blows in a particular direction in a particular season.

Anticyclone:

It is an area of high pressure with gentle winds blowing in a spiral towards the surrounding low pressure areas.

Important Questions

1. With which instrument the speed of wind is measured?

Ans. Anemometer.

2, With which instrument the direction of wind is measured?

Ans. Wind vane.

3, What is coriolis effect?

Ans. The deflection of winds due to the earth rotation is, called Coriolis Effect,

4. With which area the monsoons are mainly associated?

Ans. South and South East Asia.

5. What are katabatic winds?

Ans. Such winds which blow down mountain slopes and over adjacent lowlands are called katabatic winds.