UPSC CSE Prelims
World Geography Previous Year Questions (PYQs)
Solved Previous Year Questions (PYQs) for World Geography in UPSC CSE Prelims in English & Hindi Medium.
Chapter Breakdown: Scroll →
The term "Levant" often heard in the news roughly corresponds to which of the following regions?
Detailed Explanation:
Answer: Option 1 — Region along the eastern Mediterranean shores
The term "Levant" specifically refers to the geographical region along the eastern shores of the Mediterranean Sea, typically encompassing countries like Cyprus, Israel, Jordan, Lebanon, Palestine, Syria, and parts of southern Turkey. This region historically served as a cultural and trade crossroads connecting Anatolia, Mesopotamia, and Egypt. The term is frequently used in geopolitical contexts, especially concerning the conflicts and tensions in this area, including the Syrian Civil War and the Israeli-Palestinian conflict.
📝 Short Notes: The Levant Region
- Geographical Extent: Eastern Mediterranean coastline and its immediate hinterlands, stretching from southern Turkey to Egypt's Sinai Peninsula.
- Countries Included: Cyprus, Israel, Jordan, Lebanon, Palestine, Syria, and parts of southern Turkey.
- Historical Significance: Major trade route connecting three continents; birthplace of several ancient civilizations and religions.
- Etymology: Derived from French "levant" meaning "rising" (referring to the rising sun in the east).
- Current Relevance: Region of geopolitical importance due to ongoing conflicts, including the Syrian Civil War, Israeli-Palestinian tensions, and activities of groups like ISIS (Islamic State of Iraq and the Levant).
- Cultural Diversity: Home to diverse ethnic and religious communities including Arabs, Jews, Kurds, Christians, Muslims, and Druze.
In the northern hemisphere, the longest day of the year normally occurs in the:
Detailed Explanation:
Answer: Option 2 — Second half of the month of June
The longest day of the year in the northern hemisphere is known as the summer solstice, which typically occurs on June 20th or 21st, falling in the second half of June. On this day, the sun is directly overhead at the Tropic of Cancer (23.5°N latitude), resulting in maximum daylight hours in the northern hemisphere. The exact date may vary slightly from year to year due to the calendar system and Earth's orbital mechanics.
📝 Short Notes: Solstices and Equinoxes
| Event | Date (Approx.) | Northern Hemisphere | Southern Hemisphere |
|---|---|---|---|
| Summer Solstice | June 20-21 | Longest day, shortest night | Shortest day, longest night |
| Winter Solstice | December 21-22 | Shortest day, longest night | Longest day, shortest night |
| Spring Equinox | March 20-21 | Day and night equal | Day and night equal |
| Autumn Equinox | September 22-23 | Day and night equal | Day and night equal |
- During solstices, the sun is directly overhead at either the Tropic of Cancer (June) or Tropic of Capricorn (December)
- During equinoxes, the sun is directly overhead at the Equator, resulting in equal day and night globally
- The tilt of Earth's axis (23.5°) is responsible for seasonal variations and solstices
- The term 'solstice' comes from Latin 'sol' (sun) and 'sistere' (to stand still), as the sun appears to pause at its northernmost or southernmost position
Consider the following statements:
- High clouds primarily reflect solar radiation and cool the surface of the Earth.
- Low clouds have a high absorption of infrared radiation emanating from the Earth's surface and thus cause a warming effect.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 4 — Neither 1 nor 2
Both statements are incorrect regarding the radiative effects of high and low clouds. High clouds are thin and primarily trap outgoing infrared radiation, causing warming rather than cooling. Low clouds are thick and primarily reflect incoming solar radiation, causing cooling rather than warming.
❌ Statement 1 – Incorrect: High clouds (like cirrus) are thin and allow solar radiation to pass through but trap outgoing infrared radiation from Earth's surface, thereby warming the surface rather than cooling it.
❌ Statement 2 – Incorrect: Low clouds (like stratus and cumulus) are thick and excellent reflectors of solar radiation, reflecting sunlight back to space, thereby causing a cooling effect rather than a warming effect.
📝 Short Notes: Cloud Types and Their Radiative Effects
| Cloud Type | Altitude | Characteristics | Primary Radiative Effect | Net Impact |
|---|---|---|---|---|
| High Clouds (Cirrus, Cirrostratus, Cirrocumulus) |
6-12 km | Thin, ice crystal clouds; allow solar radiation to pass through | Trap outgoing infrared (longwave) radiation from Earth | Net Warming - Act like greenhouse gases |
| Low Clouds (Stratus, Stratocumulus, Cumulus) |
0-2 km | Thick, water droplet clouds; highly reflective | Reflect incoming solar (shortwave) radiation back to space | Net Cooling - Increase Earth's albedo |
| Middle Clouds (Altostratus, Altocumulus) |
2-6 km | Mixed composition; moderate thickness | Both reflection and absorption | Variable - Depends on thickness and composition |
- Albedo Effect: Low clouds have high albedo (30-60%), reflecting significant solar radiation, while high clouds have low albedo (10-30%).
- Greenhouse Effect: High clouds trap infrared radiation more effectively due to their cold tops and thin structure, enhancing the greenhouse effect.
- Climate Impact: Overall, low clouds have a net cooling effect on climate (~-30 W/m²), while high clouds have a net warming effect (~+10 W/m²).
- Cloud Feedback: Changes in cloud cover and types are among the largest uncertainties in climate change predictions.
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With reference to 'palm oil', consider the following statements:
- The palm oil tree is native to Southeast Asia.
- The palm oil is a raw material for some industries producing lipstick and perfumes.
- The palm oil can be used to produce biodiesel.
Which of the statements given above are correct?
Detailed Explanation:
Answer: Option 2 — 2 and 3 Only
This question tests knowledge about palm oil's origin, industrial applications, and use as biofuel. Statement 1 is incorrect as the oil palm tree is native to West Africa, not Southeast Asia, though major production now occurs in Indonesia and Malaysia. Statements 2 and 3 are correct regarding palm oil's use in cosmetics and biodiesel production.
❌ Statement 1 – Incorrect: The oil palm tree (Elaeis guineensis) is native to West Africa, not Southeast Asia. However, it was introduced to Southeast Asia in the 19th century, and today Indonesia and Malaysia account for about 85% of global palm oil production.
✅ Statement 2 – Correct: Palm oil and its derivatives are extensively used in cosmetic industries for manufacturing lipsticks, perfumes, soaps, and lotions due to their moisturizing properties and texture-enhancing qualities.
✅ Statement 3 – Correct: Palm oil is a major feedstock for biodiesel production. Countries like Indonesia and Malaysia use Palm Methyl Ester (PME) as a renewable fuel alternative, and it is blended with conventional diesel.
📝 Short Notes: Palm Oil
- Botanical Origin: Oil palm (Elaeis guineensis) is native to West and Central Africa, particularly the coastal regions of Angola, Benin, Cameroon, and Nigeria.
- Major Producers: Indonesia (58% of global production) and Malaysia (27%) are the world's largest producers, contributing about 85% of total global output.
- Industrial Uses: Food industry (cooking oil, margarine), cosmetics (soaps, lipsticks, creams), pharmaceuticals, and biofuel (biodiesel).
- Biodiesel Production: Palm oil has high oil yield (4-5 tonnes/hectare), making it economically viable for biodiesel. It is converted to Palm Methyl Ester (PME) through transesterification.
- India's Context: India is the world's largest importer of palm oil (about 8-9 million tonnes annually), primarily from Indonesia and Malaysia, meeting nearly 40% of its edible oil requirements.
- Environmental Concerns: Large-scale palm oil plantations have led to deforestation, habitat loss (especially for orangutans), and greenhouse gas emissions in Southeast Asia.
In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?
Detailed Explanation:
Answer: Option 3 — Phosphorus Cycle
The Phosphorus Cycle is unique among biogeochemical cycles as it lacks a gaseous phase and primarily relies on the weathering of phosphate-rich rocks as its main source. Geological weathering processes break down these rocks over time, releasing phosphate ions (PO₄³⁻) into the soil and water, which are then absorbed by plants and move through the food chain.
Why other options are incorrect:
• Carbon Cycle: Primarily driven by atmospheric CO₂ from respiration, combustion, and volcanic activity, not rock weathering.
• Nitrogen Cycle: Relies on atmospheric nitrogen with fixation by bacteria as the key process, not weathering of rocks.
• Sulphur Cycle: Main sources include volcanic eruptions, decaying organic matter, and fossil fuel combustion, not primarily rock weathering.
📝 Short Notes: Biogeochemical Cycles
| Cycle | Main Source of Nutrient | Key Features |
|---|---|---|
| Phosphorus Cycle | Weathering of phosphate rocks | No gaseous phase; slowest cycle; limiting nutrient in aquatic ecosystems |
| Carbon Cycle | Atmospheric CO₂ | Involves photosynthesis, respiration, combustion; has gaseous phase |
| Nitrogen Cycle | Atmospheric N₂ | Nitrogen fixation by bacteria; involves nitrification, denitrification |
| Sulphur Cycle | Volcanic activity, fossil fuels | Involves atmospheric SO₂; acid rain formation |
| Water Cycle | Oceans, water bodies | Evaporation, condensation, precipitation processes |
“Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees”. This is the most likely description of
Detailed Explanation:
Answer: Option 4 — tropical rain forest
The description perfectly characterizes tropical rain forests, where high temperature and humidity year-round create optimal conditions for rapid microbial decomposition of leaf litter, leaving the soil surface almost bare. The dense multi-layered canopy blocks sunlight to the forest floor, forcing many plants to adapt by climbing trees (lianas) or growing as epiphytes on upper branches to access light. These unique features—rapid nutrient cycling, bare soil surface, and abundant epiphytes—are hallmarks of tropical rain forests, distinguishing them from coniferous, deciduous, or mangrove ecosystems.
📝 Short Notes: Forest Biomes - Comparative Features
| Forest Type | Decomposition Rate | Soil Surface | Vegetation Characteristics | Climate |
|---|---|---|---|---|
| Tropical Rain Forest | Very rapid (fastest of all biomes) | Almost bare due to quick nutrient recycling | Dense canopy; abundant lianas, epiphytes (orchids, ferns); multi-layered structure | High temperature, high rainfall (>200 cm), high humidity year-round |
| Coniferous Forest | Very slow (cold climate inhibits decomposition) | Thick layer of undecomposed needles | Cone-bearing trees (pine, fir, spruce); needle-like leaves; limited undergrowth | Cold, long winters; moderate rainfall |
| Dry Deciduous Forest | Moderate (seasonal) | Leaf litter accumulates in dry season | Trees shed leaves in dry season; open canopy; less dense undergrowth | Distinct wet and dry seasons; 100-200 cm rainfall |
| Mangrove Forest | Slow to moderate (waterlogged, saline conditions) | Waterlogged, muddy, saline | Stilt/prop roots; pneumatophores; salt-tolerant species; sparse canopy | Coastal tropical/subtropical; tidal influence |
- Epiphytes in Tropical Rain Forests: Non-parasitic plants (orchids, bromeliads, ferns) that grow on tree branches to access sunlight without competing for soil nutrients.
- Rapid Nutrient Cycling: Despite lush vegetation, tropical rain forest soils are often nutrient-poor because nutrients are quickly absorbed by plants rather than accumulating in soil.
- Indian Distribution: Tropical rain forests in India are found in Western Ghats, Northeast states (Assam, Arunachal Pradesh), and Andaman & Nicobar Islands.
- Key Species: Mahogany, Rosewood, Ebony, Rubber, Cinchona in tropical rain forests.
Consider the following statements:
- In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
- In the temperate zone, westerlies make the eastern sections of oceans warmer than the western sections.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 3 — Both 1 and 2
Both statements correctly describe the influence of prevailing winds on ocean temperature distribution. Trade winds in tropical zones and westerlies in temperate zones drive warm surface currents in their respective directions, creating distinct temperature patterns across ocean basins.
✅ Statement 1 – Correct: Trade winds (blowing east to west) in tropical zones push warm surface waters westward, making western sections of tropical oceans warmer than eastern sections (e.g., warm Western Pacific versus cool Eastern Pacific).
✅ Statement 2 – Correct: Westerlies (blowing west to east) in temperate zones drive warm waters eastward, making eastern sections warmer than western sections (e.g., warm North Atlantic Drift warming Western Europe).
📝 Short Notes: Ocean Temperature Distribution and Wind Patterns
| Zone | Prevailing Wind | Wind Direction | Warm Ocean Section | Example |
|---|---|---|---|---|
| Tropical Zone (0°-30°) | Trade Winds | East to West | Western sections warmer | Warm West Pacific vs. Cool Peru Current (East Pacific) |
| Temperate Zone (30°-60°) | Westerlies | West to East | Eastern sections warmer | Gulf Stream/North Atlantic Drift warming Western Europe |
- Trade Winds mechanism: Push warm equatorial waters westward, causing warm water accumulation on western ocean boundaries and upwelling of cold water on eastern boundaries
- Westerlies mechanism: Drive warm currents from west to east, transferring heat from lower latitudes to higher latitudes on eastern ocean sides
- Western boundary currents: In tropical zones (e.g., Gulf Stream, Kuroshio) are warm, narrow, and fast-flowing
- Eastern boundary currents: In tropical zones (e.g., California Current, Peru Current) are cold, wide, and slow-flowing
- Climate impact: These patterns significantly influence coastal climates, with western tropical coasts being warmer and wetter, while eastern tropical coasts are cooler and drier
The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions?
- Burrowing animals and termites
- Fire
- Grazing herbivores
- Seasonal rainfall
- Soil properties
Select the correct answer using the codes given below
Detailed Explanation:
Answer: Option 3 — 2, 3 and 4
Savannah vegetation is characterized by grasslands with scattered small trees. Forest development in these areas is primarily limited by fire, grazing herbivores, and seasonal rainfall. Fire burns young tree saplings preventing forest establishment, grazing herbivores consume tree seedlings before they mature, and the distinct wet-dry seasonal rainfall pattern favors grasses over trees.
✅ Statement 2 (Fire) – Correct: Frequent fires in savannahs burn tree saplings while grasses survive due to their underground root systems and rapid regeneration.
✅ Statement 3 (Grazing herbivores) – Correct: Large herbivores consume young tree seedlings and saplings, preventing trees from establishing and maintaining grassland dominance.
✅ Statement 4 (Seasonal rainfall) – Correct: The pronounced wet and dry seasons create conditions favorable for grasses rather than dense forest growth, as trees require more consistent moisture.
❌ Statement 1 (Burrowing animals and termites) – Incorrect: While these organisms affect the ecosystem, they are not primary factors preventing forest development in savannahs.
❌ Statement 5 (Soil properties) – Incorrect: Soil properties influence vegetation types but are not the primary limiting factors for forest development in savannah regions.
📝 Short Notes: Savannah Ecosystem
- Location: Transitional climate zone between equatorial rainforests and hot deserts, found in tropical regions (Africa, South America, Australia)
- Climate Characteristics: Distinct wet and dry seasons; less rainfall than monsoon climates; temperatures remain high year-round
- Vegetation: Dominated by tall grasses (up to 3-4 meters) with scattered drought-resistant trees (acacia, baobab)
- Fire Ecology: Natural fires occur during dry season; grasses adapted to fire with underground stems; trees susceptible when young
- Herbivore Impact: Home to large grazing animals (zebras, wildebeest, elephants) that prevent tree encroachment through browsing
- Rainfall Pattern: 500-1500mm annually, concentrated in summer months; long dry season (6-8 months) limits tree growth
- Nickname: Called 'Big Game Country' due to abundant wildlife populations
With reference to the water on the planet Earth, consider the following statements:
- The amount of water in the rivers and lakes is more than the amount of groundwater.
- The amount of water in polar ice caps and glaciers is more than the amount of groundwater.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 2 — 2 Only
This question tests the understanding of Earth's water distribution. Statement 1 is incorrect because groundwater constitutes a much larger portion of Earth's freshwater compared to the relatively small volumes found in rivers and lakes. Statement 2 is correct as polar ice caps and glaciers store significantly more water than groundwater reservoirs.
❌ Statement 1 – Incorrect: The amount of water in rivers and lakes is much less than groundwater; groundwater accounts for approximately 30% of Earth's freshwater while rivers and lakes contain less than 1%.
✅ Statement 2 – Correct: Polar ice caps and glaciers contain about 68-70% of Earth's freshwater, which is significantly more than the groundwater storage.
📝 Short Notes: Distribution of Earth's Water
| Water Source | Percentage of Total Water | Percentage of Freshwater |
|---|---|---|
| Oceans (Saltwater) | ~97.5% | — |
| Freshwater Total | ~2.5% | 100% |
| Polar Ice Caps & Glaciers | ~1.75% | ~68-70% |
| Groundwater | ~0.76% | ~30% |
| Permafrost | ~0.022% | ~0.9% |
| Lakes (Fresh) | ~0.007% | ~0.26% |
| Soil Moisture | ~0.001% | ~0.05% |
| Atmosphere | ~0.001% | ~0.04% |
| Swamps & Marshes | ~0.0008% | ~0.03% |
| Rivers | ~0.0002% | ~0.006% |
| Biota | ~0.0001% | ~0.003% |
Consider the following statements:
- The Global Ocean Commission grants licences for seabed exploration and mining in international waters.
- India has received licences for seabed mineral exploration in international waters.
- ‘Rare earth minerals’ are present on seafloor in international waters.
Which of the statements given above are correct?
Detailed Explanation:
Answer: Option 2 — 2 and 3 Only
This question tests knowledge about international seabed governance and mineral resources. Statement 1 is incorrect because the International Seabed Authority (ISA), not the Global Ocean Commission, grants licenses for seabed exploration. Statements 2 and 3 are correct as India holds ISA licenses for deep-sea mineral exploration and rare earth minerals are indeed present on the international seabed.
❌ Statement 1 – Incorrect: The International Seabed Authority (ISA) regulates seabed mining in international waters, not the Global Ocean Commission, which was a 2013-2016 advisory initiative focused on ocean degradation and high seas governance.
✅ Statement 2 – Correct: India has received multiple licenses from the International Seabed Authority for seabed mineral exploration in international waters, including areas in the Central Indian Ocean Basin (since 1987, renewed in 2002 and 2017) and for polymetallic sulphides in the Indian Ocean Ridge (2016).
✅ Statement 3 – Correct: Rare earth minerals are found in polymetallic nodules and deep-sea sediments on the ocean floor in international waters, though their commercial extraction remains economically challenging.
📝 Short Notes: International Seabed Authority (ISA) and Deep-Sea Mining
- International Seabed Authority (ISA): Autonomous international organization established under UNCLOS (1994) to regulate mineral-related activities in the international seabed area beyond national jurisdiction (the 'Area').
- Headquarters: Kingston, Jamaica; 167 member states and the European Union.
- India's ISA Licenses: Pioneer Investor status (1987) for polymetallic nodules in Central Indian Ocean Basin; renewed licenses in 2002 and 2017; additional license for polymetallic sulphides exploration in Indian Ocean Ridge (2016).
- Deep-Sea Minerals: Include polymetallic nodules (manganese, nickel, cobalt, copper), polymetallic sulphides (copper, zinc, gold, silver), and cobalt-rich ferromanganese crusts containing rare earth elements.
- Global Ocean Commission: Temporary initiative (2013-2016) led by former heads of state to propose reforms for high seas governance; not a regulatory body.
- India's Deep Ocean Mission: Launched to explore deep-sea resources, develop deep-sea technologies, and enhance understanding of ocean resources including minerals in India's licensed areas.
Consider the following minerals:
- Bentonite
- Chromite
- Kyanite
- Sillimanite
In India, which of the above is/are officially designated as major minerals?
Detailed Explanation:
Answer: Option 4 — 2, 3 and 4 only
In India, major minerals are those specified in the First Schedule of the Mines and Minerals (Development and Regulation) Act, 1957. Bentonite is classified as a minor mineral, while Chromite, Kyanite, and Sillimanite are all major minerals.
1. Bentonite – Minor Mineral: Bentonite is a clay mineral used in drilling mud, foundry sand, and civil engineering applications. It is listed under minor minerals.
2. Chromite – Major Mineral ✅: Chromite is the only ore of chromium and is essential for manufacturing stainless steel and various alloys. It is a major mineral.
3. Kyanite – Major Mineral ✅: Kyanite is a refractory mineral used in ceramics and high-temperature industrial applications. It is classified as a major mineral.
4. Sillimanite – Major Mineral ✅: Sillimanite is another refractory mineral with applications in metallurgy and industrial furnaces. It is a major mineral.
📝 Short Notes: Major vs Minor Minerals in India
| Aspect | Major Minerals | Minor Minerals |
|---|---|---|
| Legal Framework | Specified in First Schedule of MMDR Act, 1957 | Specified in Second Schedule of MMDR Act, 1957 |
| Regulatory Authority | Central Government | State Government |
| Examples | Chromite, Kyanite, Sillimanite, Coal, Iron ore, Manganese, Gold, Diamond | Bentonite, Limestone (except for cement), Building stones, Gravel, Sand, Clay |
| Strategic Importance | High economic and industrial significance | Local importance, construction materials |
| Number | 64 minerals listed | Varies by state notification |
- Refractory Minerals: Kyanite and Sillimanite are aluminum silicate minerals with high heat resistance, crucial for refractory (heat-resistant) materials.
- Chromite in India: India has significant chromite reserves, mainly in Odisha (about 98% of national reserves).
- MMDR Amendment 2015: Provided greater transparency in mineral allocation through auction mechanism for major minerals.
Consider the following statements:
- Jet streams occur in the Northern Hemisphere only.
- Only some cyclones develop an eye.
- 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 ?
Detailed Explanation:
Answer: Option 3 — 2 only
Only statement 2 is correct. Jet streams occur in both hemispheres, not just the Northern Hemisphere. The eye of a cyclone is warmer than its surroundings due to adiabatic heating from subsiding air, not cooler. Only strong tropical cyclones develop a well-defined eye structure.
✅ Statement 1 – Incorrect: Jet streams occur in both the Northern and Southern Hemispheres at high altitudes (10-15 km), not exclusively in the Northern Hemisphere.
✅ Statement 2 – Correct: Only some cyclones, particularly intense tropical cyclones (hurricanes/typhoons), develop a well-defined eye at their center.
❌ Statement 3 – Incorrect: The eye of a cyclone is warmer (2-10°C higher) than the surroundings due to adiabatic heating from subsiding air, not cooler.
📝 Short Notes: Tropical Cyclones and Jet Streams
| Feature | Details |
|---|---|
| Jet Streams | Fast-moving air currents at 10-15 km altitude; occur in both hemispheres; located at boundaries between troposphere and stratosphere; influence weather patterns |
| Cyclone Eye | Calm, low-pressure center found only in intense cyclones; characterized by clear skies, light winds, and warmer temperatures |
| Eye Temperature | 2-10°C warmer than surroundings due to subsiding air compressing and heating adiabatically |
| Eye Wall | Ring of thunderstorms surrounding the eye; contains the strongest winds and heaviest rainfall |
| Cyclone Formation | Requires sea surface temperature >27°C, Coriolis force, low wind shear, and atmospheric instability |
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
- OMT is measured up to a depth of 26°C isotherm which is 129 meters in the south-western Indian Ocean during January-March.
- OMT collected during January-March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
Select the correct answer using the code given below:
Detailed Explanation:
Answer: Option 2 — 2 only
Ocean Mean Temperature (OMT) is measured up to the depth of the 26°C isotherm and serves as a reliable indicator of upper ocean heat content for monsoon prediction. Statement 1 is incorrect because the depth of the 26°C isotherm in the south-western Indian Ocean during January-March is approximately 59 meters, not 129 meters. Statement 2 is correct as OMT data collected during January-March can indeed be used to assess whether Indian Summer Monsoon Rainfall (ISMR) will be above or below the long-term mean.
❌ Statement 1 – Incorrect: The depth of 26°C isotherm is approximately 59 meters in the south-western Indian Ocean during January-March, not 129 meters.
✅ Statement 2 – Correct: OMT collected during January-March is used to predict whether ISMR will be above or below the long-term mean, making it a valuable forecasting tool.
📝 Short Notes: Ocean Mean Temperature (OMT)
- Definition: OMT is the average temperature of the ocean water column from the surface down to the depth of the 26°C isotherm (D26).
- Significance: OMT is a more stable and reliable indicator of upper ocean heat content compared to Sea Surface Temperature (SST) alone.
- Monsoon Prediction: Research by Indian Institute of Tropical Meteorology (IITM) shows that OMT data from January-March in the south-western Indian Ocean can predict Indian Summer Monsoon Rainfall with greater accuracy.
- Depth Measurement: The 26°C isotherm depth varies spatially and temporally; in the south-western Indian Ocean during January-March, it is approximately 59 meters.
- Advantage over SST: Unlike SST which can fluctuate rapidly due to surface processes, OMT represents the integrated heat content of the upper ocean layer.
- Predictive Value: Higher OMT values generally indicate favorable conditions for above-normal monsoon rainfall over India.
Consider the following pairs:
| River | Flows into |
|---|---|
| 1. Mekong | Andaman Sea |
| 2. Thames | Irish Sea |
| 3. Volga | Caspian Sea |
| 4. Zambezi | Indian Ocean |
Which of the pairs given above is/are correctly matched?
Detailed Explanation:
Answer: Option 3 — 3 and 4 only
This question tests the knowledge of major world rivers and their drainage systems. Out of the four pairs, only pairs 3 and 4 are correctly matched, while pairs 1 and 2 contain errors regarding the water bodies into which these rivers flow.
❌ Pair 1 – Incorrect: The Mekong River flows into the South China Sea, not the Andaman Sea. It originates in the Tibetan Plateau and passes through China, Myanmar, Laos, Thailand, Cambodia, and Vietnam.
❌ Pair 2 – Incorrect: The Thames River flows into the North Sea, not the Irish Sea. It flows entirely within England.
✅ Pair 3 – Correct: The Volga River, Europe's longest river, originates in Russia and correctly flows into the Caspian Sea.
✅ Pair 4 – Correct: The Zambezi River originates in Zambia and flows through several countries before emptying into the Indian Ocean via Mozambique.
📝 Short Notes: Major World Rivers and Their Drainage
| River | Region/Countries | Drains Into | Special Features |
|---|---|---|---|
| Mekong | Tibet, China, Myanmar, Laos, Thailand, Cambodia, Vietnam | South China Sea | Asia's 7th longest river; vital for Southeast Asian fisheries |
| Thames | England, UK | North Sea | Flows through London; historically significant for British trade |
| Volga | Russia | Caspian Sea | Europe's longest river (3,530 km); major transport route |
| Zambezi | Zambia, Angola, Namibia, Botswana, Zimbabwe, Mozambique | Indian Ocean | Africa's 4th longest; Victoria Falls located on this river |
| Amazon | Peru, Brazil, Colombia | Atlantic Ocean | World's largest river by discharge volume |
| Nile | Uganda, Sudan, Egypt | Mediterranean Sea | World's longest river (disputed with Amazon) |
On 21st June, the Sun
Detailed Explanation:
Answer: Option 1 — does not set below the horizon at the Arctic Circle
On 21st June, the Northern Hemisphere experiences the Summer Solstice, when the North Pole is tilted at its maximum angle (23.5°) towards the Sun. This results in the Arctic Circle (66.5°N) experiencing 24 hours of continuous daylight, meaning the Sun does not set below the horizon. Conversely, the Antarctic Circle experiences polar night, the Equator has equal day and night, and the Sun is directly overhead at the Tropic of Cancer (not Capricorn).
📝 Short Notes: Solstices and Sun's Position
| Date | Event | Sun's Position | Arctic Circle | Antarctic Circle |
|---|---|---|---|---|
| 21st June | Summer Solstice (NH) | Overhead at Tropic of Cancer (23.5°N) | 24 hours daylight (Sun does not set) | 24 hours darkness (Polar night) |
| 22nd December | Winter Solstice (NH) | Overhead at Tropic of Capricorn (23.5°S) | 24 hours darkness (Polar night) | 24 hours daylight (Sun does not set) |
| 21st March | Vernal Equinox | Overhead at Equator (0°) | 12 hours day/night | 12 hours day/night |
| 23rd September | Autumnal Equinox | Overhead at Equator (0°) | 12 hours day/night | 12 hours day/night |
- Arctic Circle: Located at 66.5°N latitude; experiences midnight sun during summer solstice
- Antarctic Circle: Located at 66.5°S latitude; experiences midnight sun during winter solstice (December)
- Tropic of Cancer: 23.5°N - Sun directly overhead on 21st June
- Tropic of Capricorn: 23.5°S - Sun directly overhead on 22nd December
- Earth's axial tilt: 23.5° from perpendicular to orbital plane causes seasonal variations