Question

Discuss the factors affecting the speed and direction of the wind.

Answer 1

Air is set in motion due to the differences in atmospheric pressure. The air in motion is called wind, which blows from high pressure to low pressure. The wind at the surface experiences friction. In addition, the rotation of the earth also affects wind movement. The force exerted by the rotation of the earth is known as the Coriolis force. Thus, the horizontal winds near the earth's surface respond to the combined effect of three forces − the pressure gradient force, the frictional force, and the Coriolis force. In addition, the gravitational force acts downward.

1. Pressure gradient force: The differences in atmospheric pressure produce a force. The rate of change of pressure with respect to distance is the pressure gradient. The pressure gradient is strong where the isobars are close to each other and are weak where the isobars are apart.

2. Frictional force: It affects the speed of the wind. It is greatest at the surface and its influence generally extends up to an elevation of 1 – 3 km. Over the sea surface, the friction is minimal.

3. Coriolis force: The rotation of the earth about its axis affects the direction of the wind. This force is called the Coriolis force. It deflects the wind in the right direction in the northern hemisphere and in nature. They oscillate with the apparent movement of the sun. In the northern hemisphere in winter they move southwards and in the summer northwards.