Question

In the figures given below, L and H indicate low and high pressure centers, respectively; PGF, CoF and CeF indicate Pressure Gradient Force, Coriolis Force and Centrifugal Force, respectively; \( V \) is Velocity. [The arrows indicate only the directions but not the magnitudes of the forces and velocity.]

Which of the following is/are the correct representation(s) of the directions of various forces and velocity in the gradient wind balance in the northern hemisphere?
 

• A. (i)
• B. (ii)
• C. (iii)
• D. (iv)

Hint:

In the northern hemisphere, the Coriolis Force always acts to the right of the velocity direction, while the Pressure Gradient Force points from high to low pressure and the Centrifugal Force acts outward.

Answer 1

The Correct Option is B, D

In the northern hemisphere, the directions of various forces and velocity in the gradient wind balance are as follows:
- Pressure Gradient Force (PGF) acts from high pressure to low pressure, causing the flow to move from high to low pressure.
- Coriolis Force (CoF) acts perpendicular to the velocity of the moving air and to the right in the northern hemisphere.
- Centrifugal Force (CeF) acts outward, away from the center of rotation.
Evaluating the options:
1. Option (i):*
In this case, the velocity is directed from low to high pressure, which is incorrect because the velocity should be directed from high to low pressure due to the action of the Pressure Gradient Force. Additionally, the Coriolis Force appears to be pointing incorrectly, and the centrifugal force is also misaligned for the gradient wind balance. Therefore, this is not a valid representation.
2. Option (ii):
This option correctly shows the Pressure Gradient Force pointing from high to low pressure, the Coriolis Force acting to the right (in the northern hemisphere), and the centrifugal force directed outward. Therefore, this is a valid representation of the gradient wind balance.
3. Option (iii)
The Pressure Gradient Force is shown as pointing from low to high pressure, which is incorrect because it should always point from high to low pressure. Thus, this is not a correct representation.
4. Option (iv):
This option correctly shows the Pressure Gradient Force pointing from high to low pressure, the Coriolis Force acting to the right, and the centrifugal force pointing outward. This is also a valid representation of the gradient wind balance.
Thus, the correct options are (B) (ii) and (D) (iv).