climatology — BSSC Geography

• The term Monsoon comes from the Arabic word “Mausim” meaning season.

• The Arabian geographer Al-Masood was among the first to study the monsoon.

• Arab sailors used the term to describe the seasonal reversal of winds over the Indian Ocean.

• Edmond Halley gave the thermal theory in 1686, not the initial wind reversal description.

• Exam Tip: Always associate “Arab sailors/geographer” with “Al-Masood” for early monsoon studies.

• Monsoon winds heavily shape India’s climate, agriculture, and economy.

• Edmond Halley gave the thermal theory in 1686, not the dynamic concept.

• Hermann Flohn provided the dynamic concepts related to the Indian monsoon’s origin in 1951.

• The thermal theory explains monsoon through the differential heating of continents and ocean basins.

• Statements 1 and 2 deliberately swap the geographers and their respective theories.

• Exam Tip: Remember “Halley = Heat (Thermal)” and “Flohn = Flow (Dynamic)”.

• This differential heating is a primary reason for the seasonal displacement indicating the Indian monsoon.

• The Tropical desert climate extends over western parts of Barmer, Jaisalmer, and Bikaner districts.

• The climate here is characterized by scanty and erratic rainfall of about 30.5 cm.

• The erratic rains in this specific region mostly occur in the form of cloud-bursts.

• The reason directly explains the characteristics that define the tropical desert classification of this region.

• Exam Tip: Jaisalmer is explicitly noted as receiving the least amount of rainfall in India.

• The mean monthly temperature in this desert climate is uniformly high, around 35°C.

• Mango Showers occur in Kerala, Karnataka, and Tamil Nadu, helping ripen mangoes.

• Nor’westers, known as Kal Baisakhi, occur in West Bengal and Assam.

• In Assam, Kal Baisakhi is specifically known by the local name Bardoli Chherha.

• Cherry Blossom marks autumn/winter blooming in Meghalaya and is beneficial for coffee.

• Exam Tip: Do not confuse Bardoli Chherha with normal Kalbaisakhi; it is the specific Assamese name.

• These are all pre-monsoon showers occurring during the hot weather season.

• The Madden-Julian Oscillation (MJO) is defined as an eastward-moving disturbance in the tropics.

• It influences rainfall and atmospheric circulation.

• When active over the Indian Ocean, the MJO enhances convection and strengthens monsoon activity over India.

• ENSO and IOD are temperature/pressure variations, not specifically “eastward-moving disturbances” like MJO.

• Exam Tip: The keyword “eastward-moving disturbance” exclusively points to MJO in climate geography.

• Western Disturbances move east but are Mediterranean-born extratropical storms, not tropical.

• The Indian Meteorological Department was established in the year 1875.

• The headquarters of the Indian Meteorological Department in 1875 was originally located in Calcutta.

• Currently, the headquarters of the IMD is located in New Delhi.

• The options with New Delhi for the original headquarters or incorrect years are traps.

• Exam Tip: IMD has 6 Regional Meteorological Centres: Mumbai, Chennai, New Delhi, Calcutta, Nagpur, Guwahati.

• IMD divides India’s climate into four main seasons: Winter, Summer, Monsoon, and Post-Monsoon.

• The IOD is indeed a climate pattern in the Indian Ocean, similar to ENSO but localized.

• A positive IOD actually enhances the monsoon, leading to above-average rainfall over India.

• A negative IOD weakens the monsoon, leading to below-average rainfall over India.

• Therefore, statements 2 and 3 are inverted and completely incorrect.

• Exam Tip: Remember “Positive = Plus (More Rain)”, “Negative = Minus (Less Rain)” for IOD.

• The IOD is driven by the difference in sea-surface temperatures in opposite parts of the Indian Ocean.

• During winter, the STWJ blows over North India, maintaining high pressure and cold conditions.

• However, it does not strengthen the northward advance; it actually blocks the northward advance of monsoon winds.

• It is only when the STWJ shifts north of the Himalayas in late May/early June that the Indian Monsoon onset is triggered.

• Thus, Reason (R) is factually false.

• Exam Tip: The Tropical Easterly Jet (TEJ) strengthens monsoon upward circulation, NOT the Westerly Jet.

• Jet streams flow in the upper troposphere at an altitude of about 8 to 15 km.

• The monsoon current reaches the Andaman and Nicobar Islands first, around 20th May.

• It then arrives at Kerala marking the mainland onset on 1st June.

• It advances up the coast, reaching areas like Mumbai around 10th June.

• Finally, the Southwest monsoon reaches the entire Indian sub-continent by 15th July.

• Exam Tip: Andaman gets rain before the mainland; always place 20th May before 1st June.

• The onset is driven by intense heating of the Indian landmass and low pressure over northwestern India.

• Under Koeppen’s classification, ‘Aw’ represents Tropical Savanna found in the Peninsular Plateau.

• Hilly Climate for regions like Himachal Pradesh, Uttarakhand, and J&K is denoted by ‘ET’, not ‘Aw’.

• ‘Amw’ correctly represents Monsoon with a short dry season on the West Coast.

• ‘As’ correctly represents Monsoon with a dry summer on the Coromandel Coast.

• Exam Tip: ‘A’ stands for Tropical climates, while ‘E’ stands for Polar/Tundra (Hilly) climates in Koeppen’s scheme.

• ‘Bwhw’ correctly matches the Semi-arid Steppe Climate of North Western Gujarat.