Question

Tropical cyclones usually do not form close to the Equator primarily because

• A. sea surface temperature at the Equator is too cold.
• B. beta effect dissipates clouds.
• C. Coriolis force is too weak.
• D. vertical shear of the zonal wind is weak.

Hint:

Cyclones require a strong Coriolis force to develop, which is why they do not form close to the Equator, where the Coriolis effect is almost zero.

Answer 1

The Correct Option is C

Tropical cyclones are large, organized systems of clouds and thunderstorms that rotate around a well-defined center. These systems are primarily driven by the latent heat released when water vapor condenses in the rising air. The rotation of the cyclone is influenced by the Coriolis force, which arises from the Earth's rotation. The Coriolis force is critical in helping create the spin that is characteristic of cyclonic motion.
Why Tropical Cyclones Don't Form Near the Equator
- Coriolis force and cyclone formation: The Coriolis force is what allows air to rotate around a low-pressure system, and its strength increases with distance from the Equator. Near the Equator, however, the Coriolis force is essentially zero, because the rotational velocity of the Earth is parallel to the surface and does not create the rotational effect needed for cyclonic motion.
- Equator and cyclone formation: At the Equator, the Coriolis effect is insufficient to generate the spin needed for cyclones to form. Cyclones need a strong rotational effect to organize the convective currents and create a low-pressure center. Without this, even if there are favorable conditions such as high sea surface temperatures, a tropical cyclone cannot form near the Equator.
Other Options Explained:
- Option (A): The sea surface temperature at the Equator is, in fact, quite warm (around 27°C or higher), which is generally favorable for tropical cyclone formation. Therefore, temperature is not the limiting factor here.
- Option (B): The beta effect (the change in the Coriolis force with latitude) affects larger-scale oceanic and atmospheric systems, but it does not prevent tropical cyclones from forming near the Equator.
- Option (D): The vertical shear of the zonal wind (winds blowing from west to east) can inhibit cyclone formation when it is strong, but it is not the primary reason for the lack of cyclones near the Equator. In fact, weaker vertical wind shear is generally favorable for cyclone formation.
Thus, the primary reason why tropical cyclones do not form close to the Equator is the weak Coriolis force near the Equator.