Consider the following statements: 1) Jet streams occur in the Northern Hemisphere only. 2) Only some cyclones develop an eye. 3) The temperature inside the eye of a cyclone is nearly 10ºC lesser than that of the surroundings. Which of the statements given above is/are correct?

The correct answer is C, only statement 2. Statement 1 is wrong because jet streams are fast, narrow westerly currents found in both hemispheres, such as the subtropical and polar jets over the Northern and Southern Hemispheres. Statement 2 is right: many cyclones, especially mature tropical cyclones, develop a calm central eye, while weaker systems and many extratropical depressions do not show a well-defined eye.

Statement 3 is wrong on the direction. The eye is a warm-core feature, and its temperature is often several degrees to about 10 degrees Celsius warmer than the surrounding environment at the same level, due to subsidence and adiabatic warming. This warm core is what sustains the low central pressure.

• Option A fails because statement 1 is false.
• Option B fails because statement 3 is false.
• Option D fails because statements 1 and 3 are both false.

Core concept: the structure of tropical cyclones and the warm-core principle, which links to Mains questions on cyclone formation, disaster management and coastal vulnerability.

Trap: reading statement 3 as "cooler" because the eye feels calm and clear, when the eye is actually warmer than its surroundings.