Physical Geography: Landforms, Climate, Oceans and Life
Core concepts
Physical geography for the BCS written paper rewards precise causal chains rather than labels. In geomorphology, know the distinction between weathering (in situ breakdown), erosion (removal), transportation and deposition; plate boundaries (divergent, convergent, transform) and their landform signatures; the Davisian cycle of erosion versus Penck's slope-replacement model; fluvial landforms (meander, oxbow, alluvial fan, delta, peneplain); glacial (cirque, arête, moraine, drumlin); aeolian (barchan, yardang, loess); and coastal (spit, tombolo, sea stack). In climatology, master the vertical structure of the atmosphere, lapse rates, the tri-cellular circulation, Coriolis deflection, jet streams, monsoon mechanics, cyclone structure and the Koppen classification logic. In oceanography, know salinity and temperature controls, thermohaline circulation, upwelling, tides (spring/neap) and coral-reef conditions. In biogeography, understand latitudinal and altitudinal zonation, soil profiles, and biome-climate correspondence.
Traps
Questions often reverse cause and effect: El Niño weakens the Walker circulation (not strengthens it); upwelling is driven by offshore-directed Ekman transport, not by wind blowing toward the coast. A second trap is confusing the ITCZ's seasonal migration with the monsoon's land-sea pressure contrast. Third, do not equate a spring tide with the spring season, and do not call a drumlin a glacial erosional feature of bedrock.
Worked example
Why is Dhaka's June rainfall far heavier than Chennai's on the same latitude? Rule of thumb: trace moisture source, lifting mechanism, and barrier. Dhaka lies in the path of the Bay of Bengal branch of the southwest monsoon, with the Meghalaya-Shillong plateau and Himalayan foothills forcing orographic ascent; Chennai faces the Arabian Sea branch and receives most rain in the retreating northeast monsoon (October-December).