Wind Formation On Earth

Wind Formation On Earth

We have all felt the gush of wind. Why is this wind sometimes fast and at other times slow? How is wind formed and what causes it to move?

Let us first learn a few facts about air that would help us understand wind better.

Winds blow from a region of low temperature to a region of high temperature because of a difference in the atmospheric pressures.

A region with a high temperature has a low-pressure condition because of low air density. A region with a low temperature has a high-pressure condition because of high air density.

We understand that a pressure difference is important in the formation and movement of winds. However, what is responsible for creating this difference in pressure?

The pressure differences exist because of the uneven heating of the Earth’s surface.

What causes an uneven heating of the Earth’s surface?

The various factors responsible for the uneven heating of the Earth’s surface and thereby for the formation of winds are listed below.

[1] Different latitudes

Owing to the tilted rays of the Sun, both the poles receive a minimum amount of sunlight. This causes the air in these regions to remain relatively cold, thereby creating a high-pressure region. The air between the 30° to 60° latitude belts is warmer in comparison to the air near the poles. Hence, this warm air rises up and cold air from the Polar Regions rush in to fill the empty space. This is depicted in the above figure.

[2] Different heating of land and water

Have you ever heard of land breeze and sea breeze?

During the summer months, the equatorial land absorbs heat and the temperature of the land becomes higher than that of the oceans. This makes the hot air from the land rise up and the cold air from the oceans blow towards the land. This results in the formation of the monsoon winds.

During winter months, the temperature of the land becomes less than that of the oceans. As a result, winds start blowing from land to the oceans.

Monsoon rain

Monsoons are seasonal winds that change their direction with changing seasons. They blow from the oceans towards land in summer and from the land to oceans in winter. When blowing from oceans to land, these winds carry water droplets with them and are responsible for the rains in India.

Other factors that influence winds:

The rotation of the Earth affects the direction of wind currents.

The rotation of the Earth on its axis causes the day and night cycle. During the day, one-half of the Earth receives sunlight and the other half is dark. Because of the rotation of the Earth, the wind currents do not flow in a straight North-South direction, but tend to flow in a curved path. The force produced by the rotation of the Earth is known as Coriolis force. It affects the direction of winds.

Summer and winter seasons affect the speed of wind currents.

The seasons are caused by the revolution of the Earth around the Sun. Air near the Earth’s surface becomes very hot during the summer months. This hot air rises upwards and creates a region of a very low pressure. Cold air comes in very fast to fill this low-pressure space. This results in the occurrence of high-speed wind currents.

On the other hand, during the winter months, wind current blows at very low speeds because of minimal pressure differences between the hot air and cold air regions