➤ The coldest months in North India are typically December and January due to the influence of continental air masses and long winter nights.
➤ During this time, temperatures drop sharply, especially in northern plains and Himalayan regions, often reaching below 5°C in many areas.
➤ Frost formation, fog, and cold waves are common in these months, particularly in Punjab, Haryana, Delhi, and Uttar Pradesh.
➤ These months are also influenced by western disturbances, which bring light rainfall and snowfall in northern regions.

★ December & January → Coldest months in North India.
★ Features → Low temperature, fog, frost, and cold waves.
★ Affected regions → Northern plains & Himalayan foothills.
★ Western disturbances → Influence winter weather in north India.

➤ Loo is a hot and dry local wind that blows across the northwestern plains of India, especially in Punjab, Haryana, Delhi, Uttar Pradesh, and Rajasthan, during the summer months of May and June.
➤ It usually occurs in the afternoon and can raise temperatures to 45°C or more, often leading to heatstroke if exposed for long durations.
➤ Loo is caused by the intense heating of the land and is a pre-monsoon phenomenon.
➤ It continues until the arrival of the southwest monsoon, which brings relief from the heat.

★ Loo → Hot, dry summer wind in north India (May–June).
★ Temperature → Often exceeds 45°C, causes heatstrokes.
★ Region affected → Punjab, Haryana, Delhi, Rajasthan, U.P.
★ Stops after → Arrival of southwest monsoon.

➤ Loo is a hot, dry wind that blows during the summer season, especially in May and June, across the northwestern parts of India.
➤ Rajasthan, due to its desert climate, experiences extremely high temperatures often exceeding 45°C, making it one of the worst-affected states by the Loo.
➤ These winds blow during the afternoon hours and can cause dehydration and heatstroke if one is exposed without protection.
➤ Southern and northeastern states like Karnataka, Kerala, and Assam do not experience the Loo, as their climate is influenced by moderating coastal or monsoonal effects.

★ Rajasthan → Severely affected by Loo winds in summer.
★ Loo → Hot, dry wind blowing in May–June across north and northwest India.
★ Temperature → Often crosses 45°C in affected regions.
★ Not found in → Coastal or northeastern states like Kerala, Karnataka, Assam.

➤ The Ganga River originates from the Gangotri Glacier in the Garhwal Himalayas (Uttarakhand), where it is known as Bhagirathi.
➤ It is one of the most sacred and longest rivers in India, flowing through northern India and into Bangladesh, where it is called the Padma.
➤ In contrast, rivers like Godavari, Tapi, and Narmada originate from the Peninsular Plateau, not the Himalayas.
➤ The Himalayan rivers are perennial, meaning they carry water throughout the year due to snowmelt and rainfall.

★ Ganga River → Originates from Gangotri Glacier, Himalayas.
★ Type → Himalayan river, perennial in nature.
★ Other options → Godavari (Nashik), Tapi (Satpura), Narmada (Amarkantak) → Peninsular rivers.

➤ Sikkim, located in the eastern Himalayas, has rugged and mountainous terrain with steep slopes and narrow valleys, making the construction of railway lines extremely difficult.
➤ Due to these challenging geographical conditions, Sikkim is the only Indian state (as of recent years) without an operational railway line.
➤ In contrast, Haryana, Bihar, and Uttar Pradesh lie in the northern plains, where flat terrain supports dense railway networks.
➤ The Sivok–Rangpo rail project is currently under development to connect West Bengal to Sikkim, but it’s still under construction due to geological and environmental challenges.

★ Sikkim → Least railway development due to mountainous terrain.
★ No operational railway line → As of recent records.
★ Rail project → Sivok–Rangpo line under progress.
★ Other states like Haryana, Bihar, U.P. → Have well-developed railway networks.

➤ The crust is the outermost solid layer of the Earth’s structure.
➤ It is thin and rigid compared to other layers and is divided into two types: continental crust (thicker) and oceanic crust (thinner).
➤ It lies above the mantle and consists mainly of silicate minerals like granite (continental) and basalt (oceanic).
➤ All life forms, landforms, and human activities occur on the Earth’s crust.

★ Crust → Outermost layer of the Earth.
★ Types → Continental (thick) & Oceanic (thin).
★ Composition → Silicate minerals like granite and basalt

➤ Tata Iron and Steel Company (TISCO), now known as Tata Steel, is one of the oldest and largest private sector companies in India, established in 1907.
➤ It is owned and operated by the Tata Group, a major Indian industrial conglomerate.
➤ In contrast, companies like SAIL (Steel Authority of India Ltd), Oil India Ltd, and BHEL (Bharat Heavy Electricals Ltd) are all public sector undertakings (PSUs) owned by the Government of India.
➤ TISCO has played a major role in India’s industrial development and is located in Jamshedpur, Jharkhand.

★ Tata Iron and Steel Company (TISCO) → Private sector company, now known as Tata Steel.
★ Established → In 1907, part of the Tata Group.

➤ Zaid season is the short cropping season in India between Rabi and Kharif seasons, usually from March to June.
➤ Cucumber, watermelon, and muskmelon are typical Zaid crops, grown in warm and dry conditions with short growing cycles.
➤ Rice is typically grown in the Kharif season, which begins with the monsoon (June–July) due to its high water requirement.
➤ Zaid crops are mostly vegetables and fruits that mature quickly and are harvested before the Kharif sowing.

★ Zaid season → Falls between Rabi and Kharif (March–June).
★ Rice → It’s a Kharif crop.
★ Typical Zaid crops → Cucumber, watermelon, muskmelon.

➤ The Bhagirathi and Alaknanda rivers meet at Devaprayag in Uttarakhand, and from this point onward, the river is known as the Ganga.
➤ This confluence is one of the Panch Prayags (five sacred river confluences) of the Alaknanda River.
➤ Devaprayag is considered a spiritually significant site and attracts pilgrims throughout the year.
➤ The Bhagirathi originates from Gangotri Glacier, and the Alaknanda originates from the Satopanth Glacier near Badrinath.

★ Devaprayag → Confluence of Bhagirathi and Alaknanda, forming the Ganga.
★ Bhagirathi origin → Gangotri Glacier; Alaknanda origin → Satopanth Glacier.
★ One of the Panch Prayags in Uttarakhand.

➤ The Himalayas act as a natural barrier and prevent the free flow of icy cold winds from Central Asia into the Indian subcontinent during the winter months.
➤ This protection ensures that northern India remains relatively warmer than other regions at similar latitudes.
➤ The lofty mountain ranges trap warm, moist winds from the Indian Ocean, contributing to heavy rainfall and a moderate climate.
➤ Without the Himalayas, India’s climatic conditions would be similar to those of Central Asia — cold and dry.

★ Himalayas → Block cold central Asian winds, protecting Indian climate.
★ Effect → Keeps northern India warmer in winters.
★ Also cause → Orographic rainfall and monsoon influence.

➤ The most common unit for measuring rainfall is millimetres (mm).
➤ Rainfall depth refers to the amount of rain that falls over a specific area during a given period, typically expressed in millimetres.
➤ One millimetre of rainfall is equivalent to one litre of water falling on a one-square-metre area.
➤ Other units like kilopascal (kPa), hectopascal (hPa), and millibar (mbar) are used for measuring atmospheric pressure, not rainfall.

★ Rainfall measurement → Commonly expressed in millimetres (mm).
★ Rainfall depth → Amount of rain over an area in millimetres.
★ Other units → Kilopascal, hectopascal, and millibar are for pressure, not rainfall.

➤ The main cause of land degradation in Jharkhand and Chhattisgarh is deforestation due to mining.
➤ These states are rich in mineral resources, and extensive mining activities lead to the destruction of forests and the degradation of land.
➤ Deforestation causes soil erosion, loss of soil fertility, and disruption of local ecosystems.
➤ Mining-related deforestation often leads to air and water pollution, further exacerbating land degradation.

★ Land degradation cause → Deforestation due to mining is the primary cause in Jharkhand and Chhattisgarh.
★ Mining impact → Leads to soil erosion, loss of fertility, and ecosystem disruption.
★ Other factors → While over-irrigation, overgrazing, and intensive use of manure contribute to land degradation, mining is the leading cause in these regions.

➤ At the time of India’s independence, well-managed industries like steel and cotton were established.
➤ The steel industry saw the establishment of Tata Steel in Jamshedpur in 1907, marking the beginning of industrialization in the country.
➤ The cotton industry was already well-established in cities like Mumbai and Ahmedabad, which were major centers for cotton mills.

➤ Afghanistan has Dari as one of its official languages.
➤ Bhutan has Dzongkha as its official language.
➤ Pakistan has Urdu as its national language and is widely spoken across the country.
➤ Myanmar has Burmese as its official language.

★ Afghanistan → Dari.
★ Bhutan → Dzongkha.
★ Pakistan → Urdu.
★ Myanmar → Burmese.

➤ Tsang Po and Jamuna are other names for the Brahmaputra river.
➤ The Brahmaputra is one of the major rivers in Asia, flowing through Tibet, India, and Bangladesh.
➤ In Tibet, it is known as Tsang Po, and as it enters India, it is called the Brahmaputra.
➤ In Bangladesh, the river is referred to as Jamuna.

★ Brahmaputra → Also known as Tsang Po in Tibet and Jamuna in Bangladesh.
★ River flow → Flows through Tibet, India, and Bangladesh.

➤ Overpopulation mostly causes land and other renewable resources to be under pressure.
➤ As the population increases, the demand for land, food, water, and energy resources also rises, leading to overexploitation.
➤ This puts immense pressure on natural resources, leading to their depletion and degradation.
➤ Overpopulation can lead to deforestation, soil erosion, and pollution, further stressing available resources.

★ Overpopulation effect → Puts pressure on land and other renewable resources.
★ Resource depletion → Leads to overexploitation and degradation of natural resources.

➤ Rivers, creeks, lakes, ponds, and streams are all considered freshwater habitats.
➤ These water bodies contain low salinity and are suitable for the survival of freshwater species.
➤ Freshwater habitats are vital ecosystems supporting a variety of plants and animals.
➤ In contrast, sea water is saline and cannot support the same species that thrive in freshwater habitats.

★ Freshwater habitats → Rivers, creeks, lakes, ponds, and streams are all classified as freshwater habitats.
★ Salinity → Freshwater habitats have low salinity, unlike sea water.

➤ The Lohit river is a tributary of the Brahmaputra river, not the Ganga.
➤ On the other hand, Yamuna, Gandak, and Kosi are all tributaries of the Ganga.
➤ These rivers contribute to the flow of the Ganga in its journey from the Himalayas to the Bay of Bengal.

★ Lohit River → A tributary of the Brahmaputra, not the Ganga.
★ Ganga tributaries → Yamuna, Gandak, and Kosi are tributaries of the Ganga.

➤ An ecosystem can be represented as a functional unit of nature.
➤ An ecosystem includes all living organisms (plants, animals, humans) and their physical environment (soil, water, air) interacting as a system.
➤ The functioning of an ecosystem involves energy flow, nutrient cycling, and the interdependence of different organisms.
➤ In contrast, vehicles, humans, and plants are parts of the natural world but not functional units in themselves like an ecosystem.

★ Functional unit of nature → An ecosystem represents the functional unit.
★ Ecosystem functions → Involves energy flow, nutrient cycling, and organism interactions.

➤ The Purvanchal Himalayas does NOT comprise the Pir Panjal range.
➤ The Pir Panjal range is located in the Northwestern Himalayas, primarily in Jammu and Kashmir, and is not part of the Purvanchal Himalayas.
➤ The Purvanchal Himalayas include ranges like the Naga hills, Manipur hills, and Mizo hills, which are located in the eastern part of India.
➤ These ranges are part of the eastern extension of the Himalayas, running through states like Nagaland, Manipur, and Mizoram.

★ Purvanchal Himalayas → Does not include the Pir Panjal range.
★ Purvanchal ranges → Includes Naga hills, Manipur hills, and Mizo hills.

➤ Majuli is the largest inhabited riverine island in the world.
➤ It is located on the Brahmaputra River in the state of Assam, India.
➤ Majuli is known for its rich culture, history, and unique ecosystem, and it is home to several Vaishnavite monasteries (Sattras).
➤ The island faces significant challenges due to erosion caused by the Brahmaputra River, but it remains a vital cultural hub.

★ Majuli → Largest inhabited riverine island in the world.
★ Located in Assam → Situated on the Brahmaputra River.

➤ The Green Revolution created regional disparities between large and small farmers in India.
➤ The Green Revolution, which began in the 1960s, introduced high-yielding variety (HYV) seeds, chemical fertilizers, and modern irrigation techniques.
➤ While it significantly increased food production, it primarily benefited large-scale farmers who could afford the expensive inputs, leaving small farmers at a disadvantage.
➤ As a result, regions with better access to resources saw greater benefits, while poorer, less developed areas struggled to keep up.

★ Green Revolution impact → Created regional disparities between large and small farmers.
★ Unequal benefits → Large farmers benefited more from modern techniques and resources.

➤ The Brahmaputra river marks the eastern-most boundary of the Himalayas.
➤ It flows through the Tibet Autonomous Region of China, India, and Bangladesh, and its basin is a significant feature of the eastern Himalayan range.
➤ The Brahmaputra originates in the Tibetan Plateau and flows eastward through the Himalayas, entering India and later Bangladesh.
➤ The river is also a key feature of the Purvanchal or eastern Himalayas, which includes regions like Assam and Arunachal Pradesh.

★ Brahmaputra River → Marks the eastern-most boundary of the Himalayas.
★ River flow → Flows through Tibet, India, and Bangladesh.

➤ Taxus wallichiana Zucc, commonly known as Himalayan yew, is a medicinal plant found in Himachal Pradesh.
➤ It is known for its medicinal properties, particularly for its use in cancer treatment, as the plant contains compounds like taxol, used in chemotherapy.
➤ The Himalayan yew is primarily found in the temperate forests of the Himalayan region, including states like Himachal Pradesh, Uttarakhand, and Jammu & Kashmir.

★ Himalayan Yew → Found in the temperate forests of Himachal Pradesh.
★ Medicinal plant → Used for cancer treatment, especially for its taxol content.

➤ The Luni River flows through the states of Rajasthan and Gujarat.
➤ The river originates in the Aravalli Range in Rajasthan and flows westward through Rajasthan before entering Gujarat.
➤ It is an ephemeral river, meaning it dries up during the summer months and is vital for the regions it flows through, although it does not reach the sea.

★ Luni River → Flows through Rajasthan and Gujarat.
★ Ephemeral river → Dries up in summer, does not reach the sea.