Climatology: UPSC Previous Year Questions (Geography)

Explanation

Option (d) is correct: The description refers to the Tropical Rainforest or Hot, Wet Equatorial Climate. In this biome, leaf litter decomposes rapidly due to high humidity and temperatures, quickly returning nutrients to the soil. As a result, the soil surface often appears bare with minimal leaf litter. They are home to climbing plants (lianas) and epiphytes (plants that grow on trees), which reach the canopy to access sunlight. These unique plant forms and rapid decomposition are characteristic features of tropical rainforests, making it a highly dynamic and nutrient-efficient ecosystem. Options (a), (b) and (c) are incorrect:

Coniferous forests (or taiga) are characterized by cold climates and slow decomposition rates. The leaf litter in coniferous forests decomposes more slowly than in tropical rainforests due to the lower temperatures and acidic nature of the soil. The description of rapid decomposition and bare soil does not match the characteristics of coniferous forests. Dry deciduous forests experience dry seasons where many trees shed their leaves. While leaf litter does decompose, the process is slower due to the dry conditions. These forests do not have the constant, year-round decomposition found in tropical rainforests. Additionally, the mention of epiphytes and climbing plants is less common in dry deciduous forests. Mangrove forests are coastal ecosystems, typically found in tropical and subtropical regions. They are characterized by salt-tolerant plants and the intertidal zone, not by the rapid de-composition of leaf litter. The soil in mangrove forests is often muddy, and the vegetation is adapted to waterlogged conditions rather than the "bare" soil and climbing plants described in the given statement.

Explanation

The Jet Stream is a geostrophic wind that generally blows from west to east across the upper layers of the troposphere at an altitude of 20,000 to 50,000 feet. Air masses with different temperatures collide to form jet streams. Thus, the location of the Jet Stream’s formation is normally characterized by surface temperatures.

Statement 1 is incorrect: Jet streams exist in both the Northern and Southern Hemispheres. They typically form near the boundaries of major air masses and are driven by temperature differences and the Earth’s rotation. The Polar Jet Stream and Subtropical Jet Stream are present in both hemispheres.

Statement 2 is correct: Not all cyclones form an eye. The eye is a distinct feature of well-developed, intense tropical cyclones. In contrast, temperate cyclones do not have an eye because there is no central area where winds and rainfall are calm or inactive.

Statement 3 is incorrect: The eye of a tropical cyclone is the calm center with the lowest surface pressure and the warmest air above it. At about 12 km high, the air in the eye can be 10°C or more warmer than the surrounding air, while at the surface, it’s only 0-2°C warmer.

Explanation

Dew formation occurs when the Earth’s surface cools down sufficiently at night, causing moisture in the air to con-dense into water droplets on cool surfaces. On clear nights, the Earth’s surface loses heat rapidly through a process called radia-tive cooling. This cooling lowers the temperature of surfaces like grass or leaves, leading to the formation of dew as the air reaches its dew point.

Option (b) is correct: On cloudy nights, the situation changes. Clouds act like a blanket, reflecting back the infrared radiation (heat) emitted by the Earth’s surface. This process is known as the greenhouse effect at a smaller scale. Because the heat is trapped, the Earth’s surface doesn’t cool enough for dew to form.

Explanation

Option (a) is incorrect: While cool sea surface temperatures can hinder cyclone formation, there are instances where localized warming (e.g., due to anomalies like El Niño) can occur in these regions. However, cyclones still rarely form, suggesting that low sea surface temperature alone isn’t the primary reason.

Option (b) is correct: In the South Atlantic and South-Eastern Pacific tropical regions, the ITCZ seldom occurs or is weak and displaced. This lack of persistent convergence means that there is insufficient atmospheric instability and rising air currents needed for cyclone formation.

Option (c) is incorrect: The Coriolis force is indeed weak near the equator, but the South Atlantic and South-Eastern Pacific are far enough from the equator for the Coriolis force to induce the necessary rotation for cyclones. Cyclones frequently form at similar latitudes in other ocean basins (e.g., the North Atlantic or the North-Western Pacific), so this isn’t the limiting factor in these regions.

Option (d) is incorrect: Cyclones form over oceans, not land, as they require moisture and heat from the sea. The absence of land actually favors cyclone formation, as land disrupts and weakens cyclones.

Explanation

Statement 1 is incorrect: Generally the westerlies flow between 30°N and 60°N and 30°S and 60°S latitude respectively, not between 30°N and 60°S latitudes.

Statement 2 is correct: The moist air masses that cause winter rains in the north-western region of India are indeed part of the westerlies. These are often referred to as winter disturbances or western disturbances, which bring moisture from the Mediterranean region, contributing to the winter rainfall in parts of India, especially the north-west.

Explanation

The passage describes a typical daily weather pattern characterized by:

Clear and bright mornings with a sea breeze.

As the Sun climbs high, heat builds up, causing dark clouds to form. Afternoon rain with thunder and lightning. The rain is short-lived, and this pattern repeats daily. This pattern is characteristic of equatorial regions, which experience convectional rainfall due to the intense heating of the Earth’s surface throughout the day. The high humidity and consistent temperatures near the equator lead to daily thunderstorms, often in the afternoon.

Explanation

Option (c) is correct: Monsoon Climate is characterized by Seasonal reversal of winds, where the wind direction changes with the seasons. It is found primarily in India, South-east Africa, Northern Australia, the Guinea Coast of West Africa and the Pacific Coast of Columbia. Summer monsoon (from June to September): Winds blow from the southwest, bringing moisture from the Indian Ocean, leading to heavy rainfall. Winter monsoon (from October to February): Winds blow from the northeast, bringing dry, cool air from the landmass.

Explanation

Tropical rainforests, also called equatorial forests, are found near the equator between the Tropics of Cancer and Capricorn. These forests thrive in areas with high temperatures and consistent rainfall, which support the rich and diverse vegetation.

Statement 1 is correct: This is a defining characteristic of tropical rainforests, also called equatorial forests. The trees are generally tall (often reaching 30-45 meters), and their crowns form a continuous canopy, which allows very little sunlight to reach the forest floor. The canopy helps in conserving moisture and maintaining the unique ecosystem.

Statement 2 is correct: Tropical rainforests are known for their high biodiversity, with a large number of species coexisting in close proximity. The climatic conditions (constant warmth and moisture) lead to intense ecological dynamics that promote coevolution, making these forests the most biodiverse terrestrial ecosystems on Earth.

Statement 3 is correct: Epiphytes, such as mosses, ferns, and orchids, are common in equatorial forests. These plants grow on other plants (usually trees) to reach sunlight, without drawing nutrients from the soil. Epiphytes are abundant in the tropics due to the high humidity and constant sunlight.

Explanation

The annual range of temperature refers to the difference between the highest and lowest temperatures over the course of a year. This range is typically higher in the interior of continents compared to coastal areas due to specific climatic factors.

Statement 1 is correct: Land heats and cools more rapidly than water due to its lower specific heat capacity. This leads to greater temperature extremes in continental interiors. In contrast, coastal areas experience moderate temperatures year-round be-cause water’s higher specific heat allows it to absorb and release heat more slowly, stabilizing the climate.

Statement 2 is incorrect: Altitude affects local temperature (higher altitudes are cooler), but it does not significantly influence the annual temperature range between coastal and interior regions. The question is about horizontal (coastal vs. interior) differences, not vertical (altitude) differences.

Statement 3 is incorrect: While winds affect the local temperature, strong winds do not have a direct relationship with the annual temperature range. Wind patterns influence the distribution of temperature but do not necessarily cause a high annual range in the interior of continents.

Statement 4 is incorrect: In fact, coastal areas usually receive more rainfall due to their proximity to large water bodies. Heavy rains tend to moderate temperatures by increasing humidity, which reduces temperature variations. Thus, this is not a factor in increasing the annual temperature range.

Explanation

The description of extreme climate, scanty rain-fall, and nomadic herding best fits the Central Asian Steppe Climate or Temperate Continental Climate or Temperate Grassland Climate:

Temperature: The continental climate of the Steppe regions is characterized by extreme temperature variations between summer and winter. Precipitation: The average rainfall is about 45 cm, but varies as per location from 25 cm to 75 cm. The heaviest rain in June and July (late spring and early summer). Lifestyle: Historically, the Central Asian Steppe was home to nomadic herders like the Kirghiz and Kazakhs, who relied on migratory animal grazing. However, nomadic lifestyles have largely declined due to modernization.