Q. The horizontal winds near the earth's surface are affected by which of the following forces?
Select the correct answer using the code given below:
Explanation:
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.
Pressure Gradient Force: The pressure-gradient force is the force that results from the difference in pressure across a surface. In general, pressure is a force per unit area, across a surface. The pressure gradient is strong where the isobars are close to each other and are weak where the isobars are apart.
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 kms. Over the sea surface, the friction is minimal.
Coriolis Force: The rotation of the earth about its axis affects the direction of the wind. This force is called the Coriolis force, named after the French physicist who described it in 1844. It 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.