Climatology: UPSC Previous Year Questions (Geography)

Explanation

Statement I is correct: Dust particles are more concentrated in subtropical and temperate regions due to the presence of dry winds. These regions often experience arid and semi-arid climates, where the lack of vegetation and strong winds promote the suspension of dust particles in the atmosphere. Deserts such as the Sahara, Thar, and Arabian Desert, all located in subtropical zones, are prime examples of major dust sources. Equatorial regions are humid and vegetated, which suppresses dust through rainfall and plant cover, while polar regions are cold and icy, limiting dust production.

Statement II is incorrect: Dry winds are prevalent in subtropical and temperate regions, and these winds are precisely the reason dust concentration is higher in these areas. In the subtropics, for example, descending air from the subtropical high-pressure belts results in dry and stable conditions, which are associated with low humidity and dusty environments.

Explanation

Statement I is correct: In January, the Northern Hemisphere’s large landmasses cool down rapidly, leading to lower temperatures. Isotherms shift southward (towards the equator) over the continents. In contrast, oceans retain heat longer, so the isotherms bend northward (poleward) when passing over oceans like the North Atlantic, where warm currents like the Gulf Stream increase the surrounding air temperature.

Statement II is correct and explains statement I: Due to the high specific heat capacity of water, oceans cool down more slowly than land. Therefore, in winter (January), the marine areas remain warmer than the adjacent continental interiors. Because of this temperature contrast the isotherms bend equatorward while crossing the landmasses and poleward while crossing the oceans in the month of January in the northern hemisphere.

Explanation

Statement I is correct: You may recall that the earth’s atmosphere is a dynamic mixture of gases that envelops the planet. It plays a great role in making the planet livable for different life forms. It provides us air to breathe, protects us from harmful ultraviolet (UV) radiation coming from the sun, traps the heat and creates a warming effect on the planet making it conducive to live by preventing extremes of temperatures. Without the atmosphere, temperatures would be well below freezing everywhere on earth’s surface.

Statement II is correct: The atmosphere helps regulate the Earth’s temperature by absorbing heat from the Sun during the day and slowing its escape at night. This heat-trapping ability is what keeps the planet’s average surface temperature around 15°C, making it suitable for life. Without this natural insulation, Earth would experience harsh temperature fluctuations between day and night, similar to what occurs on planets and moons with thin or no atmospheres.

Statement III is correct: Certain gases in the Earth’s atmosphere, particularly greenhouse gases like carbon dioxide (CO₂), methane, and water vapor, have the unique ability to absorb and trap radiation. This property makes them especially effective in trapping heat within the atmosphere, contributing significantly to the greenhouse effect.