Climatology: UPSC Previous Year Questions (Geography)

Explanation

Assertion (A) is true: The amount of atmospheric moisture varies with latitude because temperature differences across latitudes influence evaporation and condensation. Near the Equator, high temperatures increase evaporation rates, allowing the atmosphere to hold more water vapor, resulting in higher moisture content. In polar regions, lower temperatures reduce evaporation, leading to minimal moisture in the air. Reason (R) is true: The capacity of air to hold moisture is directly related to its temperature. Warmer air has a greater capacity to retain water vapor, while colder air can hold much less moisture. Since temperature is latitude-dependent, atmospheric moisture content is indirectly influenced by latitude. Reason (R) explains Assertion (A): Because temperature, which is dependent on latitude, determines the air’s ability to hold water vapor. This explains the variation in atmospheric moisture content across latitudes, with tropical regions being more humid and polar regions drier.

Explanation

Primary productivity refers to the rate at which plants and other photosynthetic organisms produce organic compounds from carbon dioxide and sunlight, forming the base of the food chain in an ecosystem. Assertion (A) is false: While temperate forest soils are generally richer in nutrients due to slower decomposition rates and seasonal leaf litter, tropical rainforest soils are nutrient-poor. The rapid decomposition in tropical rainforests causes nutrients to be quickly absorbed by the dense vegetation, leaving the soil itself infertile. Once the forest is cleared, the exposed soil is rapidly depleted due to erosion and leaching from heavy rains, making sustained agriculture difficult without chemical inputs. Reason (R) is true: The primary productivity (the rate at which plants convert sunlight into energy through photosynthesis) of tropical rainforests is indeed very high compared to temperate forests. This is due to consistent warm temperatures, high rainfall, and abundant sunlight year-round, which promote continuous plant growth. However, this high productivity is linked to the forest’s ecosystem, not the soil’s fertility.

Explanation

Assertion (A) is true: Areas located within 5° to 8° latitude on either side of the Equator, often influenced by the Intertropical Convergence Zone (ITCZ), experience year-round rainfall due to persistent solar heating and moisture-laden air masses. The ITCZ is a region where the northeast and southeast trade winds converge, causing warm, humid air to rise continuously. This rising air cools and condenses, leading to frequent cloud formation and precipitation. The consistent high temperatures in these regions enhance evaporation, while the abundant moisture ensures that convectional rainfall occurs almost daily, particularly in the afternoons when the ground has heated the most. Reason (R) is true: Convectional rainfall is characteristic of equatorial regions. High temperatures during the day cause the surface air to heat up and rise (convection), cooling as it ascends, leading to afternoon rainfall. This process is driven by the intense solar heating and high humidity near the Equator. Reason(R) explains Assertion(A): Because the continuous rainfall near the Equator is a direct result of high temperatures and convectional rain, which occurs due to the daily cycle of heating and cooling.

Explanation

Option (a) is correct: Temperate coniferous forests dominate due to their vast distribution in the boreal or taiga zones, covering large parts of North America, Europe, and Asia. They thrive in cold climates and represent the largest biome by area, accounting for the highest percentage of forest cover worldwide. Options (b), (c), and (d) are incorrect:

Temperate Deciduous Forests: Found in areas with distinct seasons, like eastern North America, Europe, and East Asia, but their global coverage is smaller than that of coniferous forests. Tropical Monsoon Forests: Found in regions with monsoon climates (seasonal rainfall) like parts of Asia and Africa, they cover a smaller area compared to temperate coniferous forests. Tropical Rain Forests: Found near the Equator, these forests are rich in biodiversity but are geographically restricted to regions like the Amazon Basin, Congo Basin, and Southeast Asia.