Climatology: UPSC Previous Year Questions (Geography)

Explanation

Statement 1 is incorrect: Equatorial regions generally experience two main seasons: a wet season (due to intense convectional rainfall) and a dry season (caused by a temporary shift in wind patterns). These regions do not have four distinct seasons like temperate zones.

Statement 2 is incorrect: In a Mediterranean climate, summers are dry due to the dominance of subtropical high-pressure systems, while winters are wet due to cyclonic activity. This climate is commonly found in areas like Southern California, parts of Australia, and the Mediterranean basin itself.

Statement 3 is correct: In China-type climate rainfall occurs throughout the year. This climate is known as the humid sub-tropical climate and is typical of regions like southern China, Taiwan, and parts of southeastern United States.

Statement 4 is correct: Tropical highlands show vertical zonation of climates, where altitude impacts temperature and vegetation. Example: In the Andes, conditions transition from tropical climates at lower elevations to temperate and alpine climates at higher altitudes. As the altitude increases, temperatures drop, and the climate changes from tropical conditions at the base to cooler temperate or even alpine climates at higher elevations.

Explanation

Albedo is the measure of a surface’s reflectivity, with higher albedo indicating greater reflection of sunlight.

Option (b) is correct: The correct sequence in decreasing order of albedo values is Tundra Taiga Tropical Deciduous Tropical Evergreen Tundra (Highest Albedo): Snow and ice dominate the Tundra landscape, leading to the highest reflectivity (albedo). Snow reflects up to 80-90% of sunlight. Taiga (Second Highest Albedo): Taiga, or boreal forests, have a lower albedo than tundra but still reflect sunlight during snowy winters. Dense coniferous forests, combined with snow, lead to moderate albedo values. Tropical Deciduous Forest - Moderate Albedo: These forests shed leaves seasonally, and during the dry season, the exposed ground and sparse canopy increase albedo slightly. Albedo ranges from 15% to 20%. Tropical Evergreen Forest - Low Albedo: Dense, evergreen canopies absorb most sunlight due to year-round leaf cover. Albedo is very low, around 10% to 15%.

Explanation

Assertion (A) is true: The 60°-65° latitudes in both hemispheres are dominated by the subpolar low-pressure belt, where the cold polar easterlies meet the warm westerlies, creating a zone of convergence. This leads to rising air and low-pressure conditions. Reason (R) is false: While oceans generally have a more stable pressure pattern due to their thermal inertia, low-pressure systems in the subpolar regions are not restricted to oceans and can also occur over land, especially in areas influenced by westerlies and cyclonic activity.

Explanation

A tropical cyclone is a powerful, rotating storm system characterized by strong winds, heavy rain, and low pressure, typically forming over warm ocean waters in tropical regions. Assertion (A) is true: In a tropical cyclone, surface winds spiral inwards toward the low-pressure center due to the Coriolis effect. The rotation direction depends on the hemisphere (counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere). Reason (R) is true: Air descends in the center of the cyclone, creating the eye of the storm, which is typically calm and free of rain. This descent is due to subsidence in the center of the low-pressure system. Reason (R) is NOT the correct explanation of Assertion (A):

The inward spiraling of surface winds is caused by the pressure gradient force pulling air toward the low-pressure center and the Coriolis effect, not by the descending air in the cyclone’s center.

Explanation

Thundercloud development, specifically cumulonimbus clouds, is influenced by various climatic and geographical factors.

Statement 1 is correct: Condensation is the process by which water vapor in the atmosphere cools and turns into liquid water droplets. For condensation to occur, the air must be saturated, and cooling must take place. This forms clouds, and in the case of thunderstorms, the towering cumulonimbus clouds. These clouds result from intense condensation when warm, moist air rises and cools.

Statement 2 is correct: High temperatures near the Earth’s surface heat the air, causing it to become lighter and rise (convection). Humidity refers to the amount of water vapor in the air. When the air is warm and moist, it carries more energy, which is essential for unstable atmospheric conditions. These conditions fuel the upward movement of air masses, leading to the formation of thunderclouds.

Statement 3 is correct: Orography refers to the influence of mountains and terrain on weather patterns. When air is forced to rise over mountains (called orographic lifting), it cools and condenses, forming clouds. This lifting mechanism often triggers thunderstorms, particularly on the windward sides of mountains where moisture-laden air ascends.

Statement 4 is correct: Vertical winds, or updrafts, are essential for the development of cumulonimbus clouds. These updrafts carry warm, moist air upward into the colder layers of the atmosphere, allowing the clouds to grow vertically. The combination of strong upward motion and moisture contributes to the towering structure of thunderclouds.

Explanation

Option (c) is correct: El Nino and Southern Oscillations (ENSO) events are known to significantly impact the Indian monsoon. During an El Niño event, sea surface temperatures in the central and eastern Pacific Ocean warm unusually. This disrupts global atmospheric circulation, including the monsoon winds. In India, this results in weakened monsoons and reduced rainfall, often leading to drought-like conditions in certain regions. The Southern Oscillation, a periodic change in atmospheric pressure between the western and eastern Pacific, works in tandem with El Niño to amplify its effects. Options (a), (b) and (d) are incorrect:

La Niña (cooler Pacific) typically strengthens the monsoon. Jet streams primarily influence monsoon onset and withdrawal, not occasional weak rainfall. Greenhouse effect, while contributing to long-term climate change, does not directly explain short-term monsoon variations.

Explanation

Option (a) is correct: The Mediterranean region is characterized by hot, dry summers and mild, wet winters. Rainfall is concentrated in the winter months (e.g., December: 11.7 cm, January: 12.2 cm) and significantly decreases during the summer months (e.g., June: 0.3 cm, July-August: no rainfall). The temperatures remain moderate year-round, ranging from 9.4°C to 15.6°C, consistent with the Mediterranean region. Winters are mild, while summers are warm but not excessively hot, due to the maritime influence. Options (b), (c) and (d) are incorrect:

Monsoon regions have rainfall concentrated in the summer months (opposite to the Mediterranean pattern). Steppe regions are semi-arid with low annual rainfall (<50 cm) and higher temperature extremes, unlike the given data. North-West Europe experiences rainfall distributed evenly throughout the year, unlike the dry summers shown in the data.

Explanation

The Roaring Forties are strong westerly winds found between 40° and 50° latitudes in the Southern Hemisphere, known for their strength due to the absence of major landmasses.

Statement 1 is incorrect: These winds are exclusive to the Southern Hemisphere, as large landmasses in the Northern Hemisphere disrupt wind flow.

Statement 2 is correct: The Roaring Forties are driven by strong pressure gradients between the subtropical high-pres-sure belt and subpolar low-pressure zone, with the Southern Hemisphere’s vast oceans enhancing their consistency.

Statement 3 is correct: The Coriolis effect causes a deflection of these winds, giving them a north-west to east trajectory.

Statement 4 is correct: These winds carry moisture, often resulting in stormy, rainy conditions, especially in the Southern Indian and Pacific Oceans.

Explanation

Option (d) is correct: The Mediterranean climate is characterized by mild, wet winters and hot, dry summers. In this climate type, the rainfall is concentrated in the winter months (typically from November to March), while the summer months experience little to no rainfall. The temperatures remain mild throughout the year, with warm, dry summers and cooler, wetter winters. The temperature in the data is warmer than typical St. Lawrence climates, and the rainfall pattern (with dry summers) doesn’t match the consistent rainfall this type usually has. The data doesn’t show the monsoon pattern with heavy summer rains and dry winters typical of the China type. The rainfall distribution in the data is more seasonal, with a distinct wet winter, unlike the West European climate, which usually has year-round moderate rainfall. Options (a), (b) and (c) are incorrect:

St. Lawrence Type: This climate has colder winters and more consistent rainfall throughout the year, unlike the distinct seasonal rainfall in the data. China Type: This climate features significant summer monsoon rainfall and drier winters, which is the opposite of the given data. West European Type: The West European climate has moderate rainfall distributed fairly evenly across the year, unlike the dry summer and wet winter pattern shown here.

Explanation

Option (c) is correct: The correct sequence of the different layers of the atmosphere from the surface of the Earth upwards is: Troposphere Stratosphere Mesosphere Ionosphere Troposphere: This is the lowest layer of the atmosphere, extending from the Earth’s surface up to about 8-15 km. It contains most of the Earth’s weather systems and clouds. Stratosphere: Above the troposphere, this layer extends from around 15 km to 50 km. It contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. Mesosphere: Above the stratosphere, the mesosphere stretches from 50 km to 85 km. It is the layer where meteors burn up upon entry into the Earth’s atmosphere. Ionosphere: This is not a distinct layer like the others but rather a region of the atmosphere (spanning from about 60 km to 1,000 km) where ionization of gases occurs. The ionosphere overlaps with the thermosphere and exosphere.