➤ The term Geoid refers to the true shape of the Earth.
➤ It represents the Earth’s shape as a slightly flattened sphere — bulging at the equator and flattened at the poles.
➤ The word “Geoid” means “Earth-shaped“, and it depicts the shape the oceans would take under Earth’s gravity and rotation, without other influences like winds and tides.
➤ It is irregular but closely resembles a sphere, more accurate than assuming Earth is a perfect sphere or ellipsoid.

★ Geoid → Actual shape of the Earth (not a perfect sphere).
★ Flattened at poles & bulging at equator → Due to Earth’s rotation.

➤ Sambhar Lake is the largest inland saltwater lake in India.
➤ It is located in the north-western part of India, specifically in the state of Rajasthan.
➤ It lies near the cities of Jaipur and Ajmer.
➤ The lake is important for salt production and is also a Ramsar Wetland Site.
➤ It is elliptical in shape and gets water from seasonal rivers like Mendha, Rupangarh, and Kharian.

★ Sambhar Lake → Largest inland salt lake of India.
★ Location → North-West India (Rajasthan).
★ Famous for → Salt production & Ramsar site.

➤ Ten Degree Channel separates the Andaman Islands (north) from the Nicobar Islands (south).
➤ It is a narrow water body in the Bay of Bengal, located at 10°N latitude.
➤ This channel is about 150 km wide and plays a significant role in India’s strategic maritime location.
➤ It is located between Little Andaman (southmost of Andamans) and Car Nicobar (northmost of Nicobars).

★ Ten Degree Channel → Separates Andaman & Nicobar Islands.
★ Location → 10°N latitude, Bay of Bengal.

➤ Kharif crops are sown at the beginning of the monsoon season, typically in June-July.
➤ These crops require a lot of water and are dependent on rainfall.
➤ They are harvested around September-October.
➤ Examples of Kharif crops include rice, maize, cotton, bajra, and jowar.

★ Kharif crops → Sown at the start of monsoon (June-July).
★ Harvested → September-October.
★ Examples → Rice, maize, cotton, bajra, jowar.

➤ Proxima Centauri is the second nearest star to Earth after the Sun.
➤ It is part of the Alpha Centauri star system, located about 4.24 light-years away from Earth.
➤ It is a red dwarf star and not visible to the naked eye.
➤ Though Sirius is the brightest star in the night sky, it is farther than Proxima Centauri.

★ Proxima Centauri → Second closest star to Earth (after the Sun).
★ Distance → About 4.24 light-years.
★ Type → Red Dwarf Star (not visible without telescope).
★ Sirius → Brightest star in night sky but not the closest.

➤ High Yielding Varieties (HYVs) had a shorter maturity period, allowing multiple cropping in a year.
➤ The adoption of HYVs was supported by greater investment in farm machinery, irrigation, fertilizers, and pesticides.
➤ HYVs actually led to an increase in cropping intensity, not a decrease, as more crops could be grown in the same area within a year.
➤ HYVs are called land-saving technology because they produce more output from the same piece of land.

★ HYVs → Short maturity, more crops per year.
★ Supported by → Use of modern farm inputs (machines, irrigation, fertilizers).
★ Green Revolution → HYVs played key role as land-saving technology.

➤ El Nino is a climate pattern associated with the unusual warming of surface waters in the central and eastern Pacific Ocean.
➤ It disrupts normal weather patterns, causing droughts in some regions and heavy rainfall in others.
➤ El Nino affects monsoons in India, often leading to weaker rainfall and drought conditions.
➤ It is part of a larger climate cycle known as ENSO (El Nino Southern Oscillation).

★ El Nino → Unusual warming of Pacific Ocean waters.
★ Impact → Disrupts global weather, especially Indian monsoons.
★ ENSO → Climate phenomenon involving El Nino and La Nina phases.

➤ Rabi crops are sown after the end of the monsoon season, typically in October-November.
➤ These crops require cooler climates for growth and are harvested in spring, around March-April.
➤ They depend mostly on irrigation rather than rainfall.
➤ Examples of Rabi crops include wheat, barley, mustard, gram, and peas.

★ Rabi crops → Sown after monsoon (Oct-Nov), harvested in spring (Mar-Apr).
★ Require → Cool climate and irrigation.
★ Examples → Wheat, barley, mustard, gram, peas.

➤ Mahendragiri is the highest peak of the Eastern Ghats, located in the Gajapati district of Odisha.
➤ It has an elevation of approximately 1,501 meters above sea level.
➤ The Eastern Ghats are discontinuous and irregular hills, unlike the Western Ghats.
➤ Mahendragiri is also associated with mythological references from the Ramayana.

★ Mahendragiri → Highest peak of Eastern Ghats (1,501 m), located in Odisha.
★ Eastern Ghats → Discontinuous and dissected hill range.

➤ Bhangar is the largest part of the northern plains and is made up of older alluvium deposits.
➤ It lies above the flood plains and is less fertile compared to Khadar due to high calcareous content (kankars).
➤ These lands are slightly elevated and do not get regular deposition of new silt.
➤ Bhangar areas are more suitable for construction and settlement due to their stability.

★ Bhangar → Largest and older alluvial part of northern plains.
★ Less fertile than Khadar due to kankar (lime nodules).
★ Located above floodplains → No fresh silt deposits.

➤ Western Disturbances are extratropical weather systems that originate over the Mediterranean Sea.
➤ These disturbances are carried by the westerly jet streams toward the Indian subcontinent.
➤ They typically arrive in India during the winter months (December to February).
➤ Western Disturbances bring winter rainfall to the north-western parts of India, which is vital for Rabi crops like wheat and barley.

★ Origin → Mediterranean Sea.
★ Brought by → Westerly jet streams.
★ Impact → Winter rainfall in North-West India.

➤ Introduced in the Union Budget 2023-24 to promote wetland conservation over the next three years. ​
➤ Objectives:
⇒ Encourage optimal utilization of wetlands.​
⇒ Enhance biodiversity and carbon stock.​
⇒ Boost eco-tourism opportunities.​
⇒ Generate income for local communities.
➤ Implementation: Focuses on sustainable ecosystem development with active participation from local communities. ​
➤ Significance: Aims to protect vital wetlands, support aquatic biodiversity, and promote sustainable livelihoods.

➤ The Narora Nuclear Power Plant is situated in the Bulandshahr district of Uttar Pradesh, India.
➤ Located near the town of Narora, along the banks of the Ganges River.
➤ The plant comprises two Pressurized Heavy Water Reactors (PHWRs), each with a capacity of 220 MW, totaling 440 MW.
➤ It is operated by the Nuclear Power Corporation of India Ltd (NPCIL).
➤ The plant plays a significant role in supplying electricity to the northern power grid of India.

★ Location → Bulandshahr district, Uttar Pradesh.
★ Reactor Type → Pressurized Heavy Water Reactors (PHWR).
★ Total Capacity → 440 MW.
★ Operator → Nuclear Power Corporation of India Ltd (NPCIL).
★ Significance → Supplies electricity to the northern power grid.

➤ Gulf of Kutch is the most promising site for tidal energy generation in India.
➤ Located on the west coast of Gujarat, it experiences a high tidal range (up to 8 meters), making it ideal for harnessing tidal energy.
➤ It was the first site in India identified for commercial-scale tidal power projects.
➤ The region has potential for both tidal stream and tidal barrage technology, although large-scale implementation is still under progress.

★ Gulf of Kutch → Leading tidal energy site in India.
★ Located in → Gujarat (west coast).
★ Tidal range → Up to 8 meters.

➤ Patkai Bum Hills are located in the easternmost part of India, primarily in Arunachal Pradesh.
➤ These hills form a part of the Purvanchal Range, which extends along the eastern boundary of India.
➤ The Patkai range is known for its dense forests and rich biodiversity.
➤ It also forms a natural border between India and Myanmar.

★ Patkai Bum Hills → Easternmost hills of India.
★ Located in → Arunachal Pradesh.
★ Part of → Purvanchal Hills.
★ Forms border → Between India and Myanmar.

➤ BHEL (Bharat Heavy Electricals Limited) is a public sector enterprise, owned and operated by the Government of India under the Ministry of Heavy Industries.
➤ It is one of India’s largest engineering and manufacturing companies, especially in power generation equipment.
➤ Bajaj Auto Ltd and Tata Steel Ltd are private sector companies.
➤ Oil India Ltd. is also a public sector company, but the correct answer here is BHEL due to its central focus in government-operated industries.

★ BHEL → Public sector company under Ministry of Heavy Industries.
★ Known for → Power generation and heavy electrical equipment.
★ Headquarters → New Delhi.
★ Other options → Bajaj Auto & Tata Steel = Private sector.

➤ Andhra Pradesh has significant mangrove forests along its eastern coastal belt, especially in the Godavari and Krishna delta regions.
➤ Mangroves are salt-tolerant trees found in intertidal coastal zones, acting as natural barriers against cyclones and erosion.
➤ The Coringa Wildlife Sanctuary in Andhra Pradesh is one of the largest mangrove forests in India.
➤ States like Rajasthan and Telangana are landlocked and do not have coastal areas for mangrove growth.

★ Andhra Pradesh → Has extensive mangrove forests in Godavari & Krishna deltas.
★ Coringa Sanctuary → Important mangrove site in A.P.
★ Mangroves → Found in coastal, saline, intertidal areas.

➤ The interior regions of Central Asia experience much harsher and colder winters due to their continental climate.
➤ In contrast, India experiences milder winters, especially in the southern and coastal regions, due to the moderating influence of oceans.
➤ India lies in the tropical and subtropical zones, hence it shows mixed climatic features.
➤ The monsoon climate is indeed dominant in South and Southeast Asia, including India.

★ India’s winters → Milder due to oceanic influence and lower latitudes.
★ Monsoon climate → Found mainly in South & Southeast Asia.
★ India’s climate → Has both tropical & subtropical characteristics.

➤ Atal Tunnel is a 9.02 km long tunnel built at an altitude of 3000 metres in the Himalayas.
➤ It connects Manali (Kullu district) to Lahaul-Spiti Valley, providing all-weather connectivity.
➤ The tunnel goes under the Rohtang Pass, which was earlier closed during winters due to heavy snowfall.
➤ It was constructed by the Border Roads Organisation (BRO) and inaugurated in October 2020.

★ Atal Tunnel → Connects Manali to Lahaul-Spiti.
★ Built by → Border Roads Organisation (BRO).
★ Altitude → 3000 meters, Length → 9.02 km.
★ Strategic Importance → Provides year-round access to Lahaul-Spiti and enhances defence connectivity.

➤ The Salal Hydroelectric Project is built on the Chenab River in the Reasi district of Jammu & Kashmir.
➤ It was the first hydroelectric project constructed in Jammu & Kashmir under the Indus Water Treaty between India and Pakistan.
➤ The project is a run-of-the-river scheme and plays a key role in power generation in North India.
➤ It has an installed capacity of 690 MW and was developed by NHPC (National Hydroelectric Power Corporation).

★ Salal Project → Located on Chenab River, J&K.
★ Type → Run-of-the-river hydroelectric project.
★ Capacity → 690 MW.
★ Significance → First hydro project under Indus Water Treaty.

➤ Shivamogga (Shimoga) is a district located in the state of Karnataka.
➤ It is rich in mineral resources, especially iron ore and manganese.
➤ These minerals are mainly found in the Bhadravati region of the district, which is also home to the Visvesvaraya Iron and Steel Plant.
➤ Karnataka is among the top producers of iron and manganese ores in India.

★ Shivamogga → District in Karnataka, rich in iron ore & manganese.
★ Bhadravati → Industrial town known for steel production.
★ Karnataka → Leading state in mineral production.

➤ Orographic rainfall occurs when a moist, saturated air mass is forced to ascend over a mountain barrier.
➤ As the air rises, it cools down, and the moisture condenses to form clouds and precipitation.
➤ The windward side of the mountain receives heavy rainfall, while the leeward side remains dry (called a rain shadow region).
➤ This type of rainfall is common in Western Ghats, Himalayas, and Northeastern hills of India.

★ Orographic Rainfall → Caused when moist air hits mountains.
★ Rainfall occurs → On windward side of the mountain.
★ Rain shadow → Dry zone on the leeward side.

➤ Tehri Hydroelectric Power Plant is located on the Bhagirathi River in the Tehri Garhwal district of Uttarakhand.
➤ The Tehri Dam, associated with this power plant, stands at a height of 260.5 meters (855 feet), making it the tallest dam in India and the 13th tallest in the world.
➤ The dam serves multiple purposes, including hydroelectric power generation, irrigation, and municipal water supply.
➤ The installed capacity of the Tehri Hydroelectric Power Plant is 1,000 MW, with plans for expansion.

★ Tehri Dam → Tallest dam in India at 260.5 meters (855 feet).
★ Location → Tehri Garhwal district, Uttarakhand.
★ River → Built on the Bhagirathi River.
★ Functions → Power generation, irrigation, and water supply.
★ Installed Capacity → 1,000 MW, with future expansion plans.

➤ Karewas are lacustrine (lake-origin) deposits found in the Kashmir Valley, part of the Kashmir Himalayas.
➤ These are thick deposits of clay, silt, sand, and boulders formed by the filling up of ancient lakes.
➤ Karewa soils are highly fertile and suitable for growing saffron, almonds, and apples.
➤ They are unique geological formations, important for paleoclimatic and seismic studies.

★ Karewa formations → Found in Kashmir Himalayas.
★ Soil type → Fertile, supports saffron and apple cultivation.
★ Formed by → Deposition in ancient lake basins.

➤ The first phase of the Green Revolution occurred during the 1960s and 1970s, focusing on Punjab, Haryana, and Western Uttar Pradesh, using HYV seeds and irrigation.
➤ The second phase took place during the 1980s, targeting dry and semi-arid regions like eastern India, central India, and parts of the Deccan plateau.
➤ It aimed to expand the benefits of the Green Revolution to areas that lacked sufficient irrigation earlier, thus encouraging a shift toward irrigated agriculture.

★ Second Phase → Took place in the 1980s, not the 60s–70s.
★ Focus → Dry & semi-arid regions of India.
★ Shift → From dry to irrigated cultivation.