Indian Geography
🔒 Log in to trackMonsoon, local winds and soils
🔒 Log in to trackMonsoon and seasons
- India has a tropical monsoon climate. The south-west monsoon normally reaches Kerala around 1 June and covers the whole country by mid-July.
- The monsoon has two branches: Arabian Sea branch (stronger; heavy rain on the Western Ghats) and Bay of Bengal branch (NE India, Gangetic plains).
- Mawsynram and Cherrapunji (Sohra) in Meghalaya record some of the world's highest rainfall (funnel-shaped Khasi hills).
- Retreating / north-east monsoon (Oct–Dec) gives most of the rain to the Tamil Nadu (Coromandel) coast.
- Leeward side of the Western Ghats (e.g. interior Karnataka, Marathwada) is a rain-shadow area.
Local winds and pre-monsoon showers
| Name | Region | Nature |
|---|---|---|
| Loo | North Indian plains | Hot, dry, dusty summer wind |
| Mango showers | Kerala, Karnataka coast | Pre-monsoon showers, help mangoes ripen |
| Cherry / Coffee blossoms | Karnataka | Pre-monsoon showers for coffee flowering |
| Kalbaisakhi (Nor'westers) | West Bengal, Assam | Violent evening thunderstorms; 'Tea showers' in Assam help tea |
| Western disturbances | Punjab, Haryana, J&K | Winter rain from the Mediterranean region; good for rabi wheat |
Soils of India (ICAR recognises 8 main groups)
| Soil | Where | Key properties / crops |
|---|---|---|
| Alluvial | Northern plains, deltas | Most widespread; khadar = new, fertile; bhangar = old, has kankar; rice, wheat, sugarcane |
| Black (Regur) | Deccan trap — Maharashtra, Gujarat, MP | Formed from basalt; rich in lime, iron, magnesium, potash; poor in nitrogen, phosphorus; high moisture retention, 'self-ploughing' cracks; cotton ('black cotton soil') |
| Red and yellow | Tamil Nadu, Karnataka, Odisha, Chhattisgarh | Red due to iron oxide; yellow when hydrated; poor in N, P, humus |
| Laterite | Western Ghats, Kerala, Odisha hills, NE | Formed by leaching under high rain and heat (Latin later = brick); good for tea, coffee, cashew after manuring |
| Arid / desert | Rajasthan | Sandy, saline, low humus; kankar layer |
| Mountain / forest | Himalayan slopes | Rich in humus, acidic |
| Saline / alkaline | Dry areas, over-irrigated Punjab–Haryana | Reh, kallar, usar; treated with gypsum |
| Peaty / marshy | Kerala (kari), Sundarbans | Heavy rain, high organic matter |
Soil erosion forms: gully erosion creates ravines (Chambal badlands); sheet erosion removes topsoil evenly. Contour ploughing, terrace farming and shelter belts check erosion.
Detailed notes
Why India has a monsoon climate
India has a tropical monsoon type of climate: the whole year turns around the seasonal reversal of winds. In summer, heated land draws in moist ocean winds - the south-west (SW) monsoon - which normally strikes the Kerala coast around 1 June ("burst of the monsoon") and normally covers the whole country by about mid-July. It has two branches: the Arabian Sea branch (dumps very heavy rain on the Western Ghats windward side) and the Bay of Bengal branch (up the Ganga plain into the north-east). By mid-September the monsoon begins to withdraw from the north-west.
Where the rain falls - and where it does not
The windward side of the Western Ghats (Mumbai, Konkan, Kerala) gets drenched; the leeward side (Pune, interior Karnataka, Marathwada) lies in the rain shadow. Mawsynram and Cherrapunji (Sohra) in Meghalaya's Khasi hills record some of the highest rainfall on Earth. Rajasthan's west (Jaisalmer) stays driest. A long dry spell inside the season is called a break in the monsoon. The El Nino warming of the eastern Pacific is linked with weaker Indian monsoons.
The retreating monsoon and local winds
In October the monsoon winds leave; hot, humid days of this month are called October heat. As the winds retreat south they pick up moisture from the Bay of Bengal and give October-December rain to the Tamil Nadu (Coromandel) coast - the north-east (NE) monsoon, Tamil Nadu's main rain. Pre-monsoon and local winds asked in exams:
| Name | Region | Nature / use |
|---|---|---|
| Loo | North Indian plains | Hot dry summer wind |
| Mango showers | Kerala, Karnataka coast | Help mango ripen |
| Blossom showers | Karnataka | Help coffee flower |
| Kalbaisakhi / Nor'westers | West Bengal, Assam | Evening thunderstorms; help tea and jute; Bordoichila in Assam |
| Western disturbances | Punjab, Haryana, west UP, J&K | Winter rain from the Mediterranean area; vital for rabi wheat |
Soils of India (ICAR recognises 8 groups)
| Soil | Where | Key facts |
|---|---|---|
| Alluvial | Northern plains, deltas | Most widespread (about 40% of area); khadar = new & fertile, bhangar = old with kankar; rice, wheat, sugarcane |
| Black (Regur) | Deccan trap - Maharashtra, Gujarat, MP | From basalt; rich in lime, iron, magnesium, potash; poor in nitrogen, phosphorus, humus; holds moisture; "self-ploughing" cracks; cotton |
| Red and yellow | TN, Karnataka, Odisha, Chhattisgarh | Red colour from iron oxide; sandy, poor in humus |
| Laterite | Western Ghats, Kerala, Odisha hills, NE | Formed by leaching in heat + heavy rain; hardens like brick (Latin later); tea, coffee, cashew after manuring |
| Arid | West Rajasthan | Sandy, saline, calcium (kankar) layers |
| Saline / alkaline | Dry areas; over-irrigated Punjab-Haryana | Reh, kallar, usar; reclaimed with gypsum |
| Peaty / marshy | Kerala (kari), Sundarbans | High humus, black, heavy |
| Forest / mountain | Himalayan slopes | Rich humus, acidic |
Soil erosion and its cure
Running water cuts gully erosion, which turns land into bare ravines (the Chambal badlands); even removal of the topsoil layer is sheet erosion; open land in dry areas suffers wind erosion. Remedies: contour ploughing, terrace farming, strip cropping, shelter belts of trees, afforestation.
Quick revision
- SW monsoon hits Kerala about 1 June; two branches - Arabian Sea and Bay of Bengal; withdraws from NW by mid-September.
- Rain shadow on the leeward Ghats; Mawsynram wettest; Tamil Nadu's main rain from the retreating (NE) monsoon in Oct-Dec.
- Loo = summer north India; mango showers = Kerala; blossom = coffee; Kalbaisakhi = Bengal-Assam tea.
- Black soil: basalt, cotton, rich in LIMP, poor in N-P-humus. Laterite: leaching, brick-hard. Saline soil treated with gypsum.
- Alluvial is the most widespread soil; gully erosion makes Chambal ravines.
Types of questions asked
Every way this subtopic shows up in exams — how to recognise it, the formula or logic to use, and a solved example.
Type 1: SW monsoon: onset, branches and withdrawalvery common3 practice Q
Questions on when and where the monsoon strikes Kerala, its two branches, when it covers the country, or when it starts withdrawing.
- Onset: SW monsoon normally bursts on the Kerala coast about 1 June and covers most of India by mid-July.
- Two branches: the Arabian Sea branch (heavy rain on the windward Western Ghats) and the Bay of Bengal branch (north-east, then up the Ganga plain).
- Withdrawal begins from the north-west around mid-September; the monsoon season is roughly June to September.
Example: The south-west monsoon normally sets in over the Kerala coast around —
1 June. From Kerala it advances north in two branches and normally covers the whole country by mid-July.
Type 2: Rainfall distribution, rain shadow and extremesvery common4 practice Q
'Which region gets the highest/lowest rainfall?', 'Why is Pune/Deccan dry?', 'rain shadow of the Western Ghats', 'Mawsynram is in which state?'
- Windward side of the Western Ghats (Konkan, Kerala, Mumbai) = very heavy rain; the leeward side (Pune, interior Karnataka, Marathwada) lies in the rain shadow.
- Wettest spots: Mawsynram and Cherrapunji (Sohra) in Meghalaya; driest: western Rajasthan (Jaisalmer).
- Tamil Nadu's coast stays comparatively dry in June-September because it lies in the rain shadow and is oriented away from the SW monsoon - its main rain comes later (NE monsoon).
Example: Mawsynram, one of the rainiest places on Earth, lies in which state?
Meghalaya, in the Khasi hills. Cherrapunji (Sohra) is the other famous wet station nearby.
Type 3: Retreating monsoon, October heat and local windsvery common4 practice Q
'Kalbaisakhi is associated with', 'mango showers help which crop', 'October heat', 'which wind brings winter rain to Punjab'.
- October: winds retreat, days hot and humid - October heat. The retreating winds pick up moisture from the Bay of Bengal and give Oct-Dec rain to the Tamil Nadu coast (NE monsoon).
- Showers: Mango showers (Kerala-Karnataka, mango), Blossom showers (Karnataka, coffee), Kalbaisakhi/Nor'westers (Bengal-Assam, tea-jute; Bordoichila in Assam).
- Winter: Western disturbances from the Mediterranean region give rain to Punjab, Haryana, west UP and J&K - vital for rabi wheat.
Example: Kalbaisakhi (Nor'wester) thunderstorms, which benefit the tea and jute crops, occur mainly in —
West Bengal and Assam in spring (March-May). In Assam the same season brings the Bordoichila winds.
Type 4: Soil type ↔ properties, formation and cropsvery common4 practice Q
'Regur soil is best for', 'which soil is formed by leaching', 'black soil is deficient in', 'khadar and bhangar are types of'.
- Match soil to formation: alluvial - river deposits (khadar new, bhangar old with kankar); black (regur) - basalt; red/yellow - iron oxide; laterite - intense leaching; arid - desert; peaty - Kerala (kari).
- Black soil: rich in lime, iron, magnesium, potash; poor in nitrogen, phosphorus and humus; self-ploughing cracks; ideal for cotton.
- Laterite hardens into bricks when exposed; saline-alkaline soil (reh, usar) is reclaimed with gypsum.
Example: Black (regur) soil is well known for being deficient in —
Nitrogen, phosphorus and humus. It is rich in lime, iron, magnesium and potash, and holds moisture well - hence its value for cotton.
Type 5: Soil erosion and conservationoccasional2 practice Q
'Ravines of the Chambal are an example of', 'contour ploughing is used for', 'sheet erosion means'.
- Gully erosion (running water) turns land into useless ravines - the Chambal badlands of MP-Rajasthan-UP.
- Sheet erosion removes the topsoil uniformly; wind erosion strips dry open land.
- Remedies: contour ploughing, terrace farming, strip cropping, shelter belts, afforestation.
Example: The bare, gullied badlands along the Chambal river are a classic example of —
Gully erosion by running water, which cuts the alluvial land into deep ravines unfit for cultivation.
Shortcut tricks
⚡ Black soil rich/poor list
Rich in 'LIMP' — Lime, Iron, Magnesium, Potash. Poor in 'NPH' — Nitrogen, Phosphorus, Humus.
Example: Black soil is generally deficient in which nutrient?
Nitrogen (also phosphorus and organic matter).
⚡ Shower names by crop
Mango showers → mango (Kerala); Blossom showers → coffee (Karnataka); Kalbaisakhi → tea/jute/rice (Bengal, Assam). Western disturbances → wheat (rabi) in the north-west.
Where students lose marks
Saying Tamil Nadu gets most rain from the south-west monsoon — it gets most in Oct–Dec from the retreating/north-east monsoon.
Attributing red colour of red soil to aluminium — it is iron oxide.
Treating laterite as naturally fertile — it is leached and needs manure.
Practice sets — 19 questions
Sets of 10, mixed across the question types above. Each answer comes with a step-by-step explanation.
Topic test · 10 questions
Suggested time 4 min · wrong answers go to your mistake notebook automatically.