निम्नलिखित कथनों पर विचार कीजिए :
- 1.जेट प्रवाह केवल उत्तरी गोलार्ध में होते हैं ।
- 2.केवल कुछ चक्रवात ही केंद्र में वाताक्षि उत्पन्न करते हैं ।
- 3.चक्रवात की वाताक्षि के अन्दर का तापमान आसपास के तापमान से लगभग 10°C कम होता है ।
उपर्युक्त कथनों में से कौन-सा/से सही है/हैं ?
Read this question in English
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 10°C lesser than that of the surroundings.
Which of the statements given above is/are correct?
(a) 1 only · (b) 2 and 3 only · (c) 2 only · (d) 1 and 3 only
उत्तर और व्याख्या · explanation in English
Answer: (c) केवल 2
Only statement 2 is correct. Jet streams blow in both hemispheres, and the eye of a tropical cyclone is warmer, not colder, than its surroundings; but an eye forms only once a cyclone has organised and intensified.
- ✗ 1. Jet streams exist in both hemispheres. The polar jet lies between about 50° and 60° latitude in the northern and the southern hemispheres alike.
- ✓ 2. An eye develops only when the inner spiral bands close into an eyewall, which usually happens around the time winds reach hurricane force. Weak tropical systems and temperate (extra-tropical) cyclones generally have no eye.
- ✗ 3. The eye is the region of lowest surface pressure and, aloft, the warmest air; a tropical cyclone has a warm core, so the eye is warmer than its surroundings, not cooler.
Remember · Jet streams occur in both hemispheres. A cyclone's eye forms only in mature tropical cyclones, and it is a calm, warm-cored centre.
Sources
- US National Weather Service / NOAA JetStream: The Jet Stream ↗ “The polar jet is located between the 50°-60° latitude lines in both the northern and southern hemispheres.”
- NOAA Hurricane Research Division FAQ: life cycle of a hurricane ↗ “the inner bands will close off into an eyewall, surrounding a central calm area known as the eye. This usually happens around the time wind speeds reach hurricane force. … The eye is the region of the lowest pressure at the surface and the warmest temperatures at the top.”
Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·