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Glossary Terms
| Term (EN) | Definition | Exam Relevance |
|---|---|---|
| Monsoon | Seasonal reversal of wind direction causing wet/dry seasons | Core topic |
| ITCZ | Inter-Tropical Convergence Zone — belt where NE and SE trade winds meet; migrates seasonally | Monsoon mechanism |
| SW Monsoon | June–September; brings 70–90% of India's annual rain | Core topic |
| NE Monsoon | Oct–Dec; land-to-sea wind; brings rain to Tamil Nadu (60% of annual) | PYQ pattern |
| El Niño | Anomalous warming of central/eastern equatorial Pacific; weakens Indian monsoon | PYQ 2023 — 10 marks |
| La Niña | Anomalous cooling of equatorial Pacific; typically strengthens Indian monsoon | PYQ 2023 context |
| Walker Circulation | East-west atmospheric circulation over Pacific; weakened by El Niño | ENSO mechanism |
| Indian Ocean Dipole | Temp. difference between western and eastern Indian Ocean; affects monsoon | Monsoon variability |
| Western Disturbance | Mid-latitude cyclone from Mediterranean travelling east; brings winter rain to NW India | PYQ 2023 — 10 marks |
| Jet Stream | Fast upper-level air current; Subtropical Westerly Jet (25°–35°N) drives WDs | Atmospheric circulation |
| Tibetan High | Upper tropospheric anticyclone over heated Tibetan Plateau; drives monsoon | PYQ 2023 — 10 marks |
| Rain Shadow | Dry area on leeward side of a mountain range; e.g., Deccan behind Western Ghats | Rainfall distribution |
| Orographic Rainfall | Rain forced when moist air rises against a mountain; cools and condenses | Western Ghats |
| Loo | Hot, dry dusty wind over NW India; April–June; temperatures 45–50°C | Summer season |
| Kalbaisakhi | Pre-monsoon nor'west thunderstorms in Bengal/Assam (April–May) | Weather events |
| Mango Showers | Pre-monsoon rains in Kerala/Karnataka (May); benefits mango, coffee crops | Pre-monsoon events |
| Break Monsoon | Dry spell mid-monsoon when ITCZ shifts north to Himalayas | Monsoon variability |
| Koppen Am | Tropical Monsoon climate — high rainfall, brief dry month | Climate classification |
| Koppen BWh | Hot desert climate — <250 mm rainfall, extreme heat | Thar Desert climate |
| Koppen Cwa | Humid subtropical with dry winter; Ganga plains | North India climate |
| Mawsynram | World's wettest place — 11,871 mm/year; Meghalaya (Khasi Hills) | Rainfall extremes |
| Somali Jet | Low-level jet stream that drives Arabian Sea branch of SW monsoon | Monsoon mechanism |
| MJO | Madden-Julian Oscillation — 30–60 day atmospheric wave affecting monsoon variability | Advanced monsoon |
| Agro-climatic Zone | Region with uniform climate and agricultural suitability; 15 zones (Planning Commission) | Agricultural geography |
| ENSO | El Niño-Southern Oscillation — coupled ocean-atmosphere phenomenon driving climate variability | Climate science |
Sources: India Meteorological Department (IMD); NCERT Class 11 Fundamentals of Physical Geography; NCERT India — Physical Environment; RPSC Mains PYQ 2013–2023; WMO Climate Reports.