Which of the following is the reason of the storms in Arabian sea and Bay of Bengal on the border of the Indian Peninsula ?

Question

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Correct — option (2), 'due to increase in temperature and decrease in air pressure,' names the actual causal chain behind the storms that form over the Arabian Sea and the Bay of Bengal along the edges of the Indian Peninsula, mainly in the pre-monsoon (April-May) and post-monsoon/retreating-monsoon (October-December) windows. It starts with sea-surface temperature: tropical cyclogenesis generally needs the sea surface warmed to roughly 26-27°C or more. Once the surface is that warm, evaporation off the sea intensifies, pumping large volumes of water vapour and latent heat into the air directly above it. That warm, moisture-laden air is buoyant, so it rises; and as it rises away from the surface, the air pressure at the surface beneath it falls, because there is now less air mass sitting directly overhead. This falling surface pressure is exactly what a meteorologist means by a 'low' — a shallow trough that, given continued convection, deepens into a depression. As the rising moist air cools with height, its water vapour condenses into cloud, releasing further latent heat that reinforces the updraft and deepens the low still more. Provided other conditions are also met — Coriolis force strong enough to organise rotation (which is why cyclones do not form very close to the equator), low vertical wind shear so the storm's vertical structure is not torn apart, and upper-level divergence to keep pulling air out of the top of the system faster than it is fed in at the surface — this deepening low can organise into a depression and then a cyclonic storm. So the two-variable pairing the question asks for is genuinely causal, not coincidental: the temperature rise is the energy source, and the pressure fall is the direct, physical consequence of the warm air rising away from the surface. This basic mechanism is why both seas flanking the Peninsula, despite lying on opposite coasts, produce storms through the same underlying process.

Why the other options are wrong — (a) This is the description of a cooling, subsiding, stable air mass — essentially an anticyclone — which is the physical opposite of what drives a storm. Falling temperature reduces evaporation and convection rather than fuelling it, and rising pressure means air is sinking and spreading out at the surface, not rising and organising into a low. A storm cannot form under these conditions; they describe fair, settled weather, not cyclogenesis.  (c) Half of this option is right and half breaks the physics: temperature genuinely rises (that is the energy source), but pressure does not rise alongside it — it falls. The rising warm, moist air is precisely what lowers the surface pressure beneath it, because that column of air is now lighter and there is less air mass pressing down. A simultaneous rise in both temperature and pressure would actually suppress the convection a storm needs, not enable it; the question is testing whether a candidate notices that these two variables move in opposite directions here, not the same one.  (d) This option gets the pressure half right — the surface pressure genuinely does fall as the storm organises — but gets the temperature half backwards. It is a rise in sea-surface temperature, not a fall, that supplies the evaporative moisture and latent heat which powers the whole convective process in the first place. A cooling sea surface would starve the storm of the energy it needs rather than help it form.

Concept: Tropical cyclogenesis over the seas around the Indian Peninsula follows a standard causal chain: a warm sea surface (conventionally at or above roughly 26-27°C) drives intense evaporation and latent-heat transfer into the overlying air; that warm, moist air rises; its rise lowers the surface air pressure beneath it, creating a shallow low/trough; condensation as the air cools with height releases further latent heat, deepening the low into a depression; and, given adequate Coriolis force (so cyclones are rare within about 5° of the equator), low vertical wind shear, and upper-level divergence to keep venting air out of the system's top, the depression can intensify into a cyclonic storm. The temperature-rise-causes-pressure-fall relationship is the crux this question tests.

State PCS 2025 Q28 — Geography PYQ with Answer

State PCS 2025 Q28 — Geography PYQ with Answer