Climatology and Oceanography
What this domain tests
This domain covers atmospheric structure and processes - insolation, temperature, pressure, winds, humidity, condensation, precipitation and the Indian monsoon - and oceanography: ocean-floor relief, salinity, temperature, currents, tides and coral reefs. Expect cause-and-effect questions and simple calculations.
Core rules
- Troposphere holds weather; stratosphere holds the ozone layer; temperature falls with height in the troposphere at the normal lapse rate of about 6.5°C per km.
- Pressure belts: equatorial low, subtropical high, subpolar low, polar high. Winds blow from high to low pressure, deflected by the Coriolis force.
- Indian monsoon: southwest monsoon (June–September) gives rain to most of India; the northeast monsoon (October–December) brings rain to coastal Andhra Pradesh and Tamil Nadu. ENSO and the Indian Ocean Dipole modulate rainfall.
- Ocean floor: continental shelf, slope, rise, abyssal plain, trench, mid-ocean ridge. Average salinity is about 35 parts per thousand; it is higher in the subtropics and lower near the equator and river mouths.
- Currents are warm when moving from low to high latitudes (Gulf Stream, Kuroshio) and cold when moving from high to low latitudes (Canary, Humboldt). Spring tides occur at new and full moon; neap tides at quadrature.
Worked example
A hill station at 1,800 m records 18°C while the sea-level plain records 30°C. Expected fall = 1.8 × 6.5 = 11.7°C, so the hill should be 30 − 11.7 = 18.3°C. The close match confirms the normal lapse rate; a much warmer hill would suggest a temperature inversion or foehn effect.
Traps
Saying temperature rises with height in the troposphere; confusing spring and neap tides; treating the northeast monsoon as unimportant for Andhra Pradesh; quoting salinity without units or variation.