Assertion (A): The western coasts of continents in subtropical latitudes tend to be arid or desert regions. Reason (R): Cold ocean currents flowing equatorward along these coasts stabilize the lower atmosphere, reducing evaporation and suppressing cloud formation and precipitation.

💡 Solution & Explanation

Subtropical coastal deserts such as the Atacama, Namib, and Sahara margins are largely maintained by cold ocean currents like the Humboldt and Benguela currents that cool the overlying air, increasing relative humidity near the surface without causing condensation or convective uplift. This atmospheric stabilization prevents cloud development, resulting in arid conditions despite proximity to ocean waters. Descending branches of subtropical high-pressure cells reinforce this aridity.