Climatology for Kerala PSC: Forces Affecting the Velocity and Direction of Wind
July 1, 2022 2022-07-01 16:24Climatology for Kerala PSC: Forces Affecting the Velocity and Direction of Wind
● The Factors affecting the velocity and Direction of Wind are:
1. The pressure gradient force
2. The frictional force
3. The Coriolis forces
Pressure Gradient Force
● The difference in atmospheric pressure produces 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 is weak where the isobars are apart.
● If the pressure gradient is strong the velocity of wind is higher.
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. The velocity of the wind decreases with the increase in frictional force.
Coriolis Force
● The rotation of the earth about its axis creates Coriolis force that affects the direction of the wind.
● This Coriolis force deflects the wind to the right direction in the northern hemisphere and to the left in the southern hemisphere.
● The deflection is more when the wind velocity is high.
● The Coriolis force is directly proportional to the angle of latitude. It is maximum at the poles and is absent at the equator.
● The Coriolis force acts perpendicular to the pressure gradient force. The pressure gradient force is perpendicular to an isobar.
● The higher the pressure gradient force, the more is the velocity of the wind and the larger is the deflection in the direction of the wind.
Ferrel’s Law
● According to this law, the winds turn toward their right in the Northern Hemisphere and to their left in the Southern Hemisphere.
● The winds are deflected from their true gradient course as a result of the Coriolis force which is generated by the rotation of the earth.