Question

Which of the following statement(s) is/are true about northern hemisphere tropical cyclones?

• A. They have a warm core.
• B. Their low-level flow is cyclonic.
• C. Strong wind shear in the vertical is required for their intensification.
• D. They are characterized by upper-level divergence.

Hint:

Tropical cyclones have a warm core, low-level cyclonic flow, and upper-level divergence, all of which help in maintaining the cyclone's intensity.

Answer 1

The Correct Option is A, B, D

Tropical cyclones in the northern hemisphere are characterized by specific physical features that distinguish them from other atmospheric systems. Let's go through each statement to understand why (A), (B), and (D) are correct:
(A) They have a warm core.
This statement is true. Tropical cyclones are characterized by a warm core, meaning the center of the storm is warmer than the surrounding environment. This warmth is caused by the release of latent heat during condensation, which powers the storm. This warm core is a key feature that differentiates tropical cyclones from extratropical cyclones, which have a cold core. (B) Their low-level flow is cyclonic.
This statement is true. In the northern hemisphere, the low-level flow in a tropical cyclone is cyclonic, meaning it rotates counterclockwise (viewed from above). This is due to the Coriolis force, which causes the air to rotate around a low-pressure center in a counterclockwise direction in the northern hemisphere. (C) Strong wind shear in the vertical is required for their intensification.
This statement is false. Strong vertical wind shear (a change in wind speed and direction with height) actually inhibits the development and intensification of tropical cyclones. Tropical cyclones thrive in environments with low vertical wind shear, allowing the storm to remain vertically aligned and strengthen. High wind shear can tilt the storm and disrupt the central convection, preventing it from becoming stronger. (D) They are characterized by upper-level divergence.
This statement is true. Tropical cyclones are associated with upper-level divergence, where the air at the top of the storm is moving away from the center. This divergence at upper levels allows air to rise and continue fueling the storm's convection. The outflow of air in the upper atmosphere is critical for the storm's sustained intensity. Thus, the correct answers are (A), (B), and (D).