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Glossary Terms
| Term (EN) | Definition | Exam Relevance |
|---|---|---|
| Insolation | Incoming solar radiation received at Earth's surface | Core atmospheric Q |
| Albedo | Fraction of incoming solar radiation reflected by a surface (fresh snow 80–90%) | Insolation Q |
| Hadley Cell | Atmospheric circulation cell (0°–30°); equatorial rising air, subtropical descent | Circulation Q |
| Ferrel Cell | Mid-latitude indirect circulation cell (30°–60°); surface westerlies | Circulation Q |
| Trade Winds | Reliable winds from subtropical highs to equatorial low; NE in NH, SE in SH | Wind system Q |
| Westerlies | Winds from subtropical to subpolar regions (30°–60°); SW in NH, NW in SH | Wind system Q |
| Coriolis Effect | Earth's rotation deflects winds right (NH) and left (SH) | Wind direction Q |
| Jet Stream | Fast narrow upper-air currents (9–16 km altitude; 120–400 km/h) | Upper air Q |
| Relative Humidity | Actual vapour as % of saturation vapour at same temperature; measured by psychrometer | Humidity Q |
| Dew Point | Temperature at which air becomes saturated (100% RH) | Condensation Q |
| Convectional Rain | Rain from surface heating → rising moist air → condensation; intense, localised | Precipitation type Q |
| Orographic Rain | Rain from moist air forced upward by mountains; windward heavy; leeward rain shadow | Cherrapunji example |
| Frontal Rain | Rain from warm and cold air mass meeting; widespread, prolonged | Temperate climate Q |
| El Niño | Anomalous warming of eastern Pacific; weakens Indian monsoon | PYQ 2016 — 5 marks |
| La Niña | Cooling of eastern Pacific; opposite of El Niño; strengthens Indian monsoon | ENSO Q |
| SOI | Southern Oscillation Index; Tahiti minus Darwin pressure; negative = El Niño | ENSO measurement |
| Mediterranean Climate | Dry hot summer + wet mild winter; 5 global regions | PYQ 2013 |
| Polar Front | Boundary between cold polar and warm mid-latitude air masses; subpolar low | Frontal rain Q |
| Walker Circulation | East-west atmospheric circulation in tropical Pacific; disrupted by El Niño | ENSO Q |
| Subtropical High | Descending Hadley Cell air at 25°–35°; source of subtropical deserts | Pressure belt Q |
| Psychrometer | Instrument with wet and dry bulb to measure relative humidity | Humidity measurement |
| Precipitation | Any form of water falling from clouds: rain, snow, sleet, hail, drizzle | Core topic |
| Roaring Forties | Strong westerly winds at 40°S in Southern Hemisphere; historically used by sailing ships | Wind system Q |
| Köppen System | Most used climate classification: 5 groups (A–E) based on temperature and precipitation | Climate type Q |
| Rain Shadow | Dry area on leeward side of mountains; opposite of orographic rainfall zone | Desert formation |
Sources: NCERT Physical Geography Class XI; Trewartha's Climate Classification; WMO (World Meteorological Organisation) publications; NOAA El Niño/La Niña monitoring data; INCOIS climate bulletins; Barry & Chorley Atmosphere, Weather & Climate; RPSC Mains PYQ 2013–2023.