Discussion
A rotating weather system has a tangential velocity of 100 m s-1, diameter of 1 km, and located at a latitude where the Coriolis parameter is 10−4 s-1. Which one of the following statements is true about this weather system?
Answer: D
The system is in cyclostrophic balance.
Compare the centrifugal and Coriolis terms through the Rossby number, using the radius R = 0.5 km:
\[ Ro = \frac{V}{fR} = \frac{100}{10^{-4} \times 500} = 2000 \]
The centrifugal acceleration \(V^{2}/R\) is two thousand times the Coriolis acceleration \(fV\), so the Coriolis force is negligible and the pressure gradient force is balanced by the centrifugal force alone. That is cyclostrophic balance, typical of tornadoes and dust devils.
Geostrophic balance needs \(Ro \ll 1\), and gradient wind balance matters when both terms are comparable. A cyclostrophic vortex always has low pressure at its centre, since the pressure gradient must point inward, so it cannot be a high-pressure system.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development