Major hot deserts in the Northern Hemisphere are located between 20°–30° North and on the western side of the continents. Why? (UPSC 2013)

Major hot deserts are concentrated in the Northern Hemisphere between 20°–30° N because this belt lies under the descending limb of the Hadley cell. The sinking air is compressed, warms up, and becomes dry, so cloud formation and rainfall are suppressed.

• Subtropical high-pressure belt: Persistent anticyclones dominate this zone, causing stable, dry weather.
• Trade winds and western margins: Easterly trade winds lose moisture on eastern coasts and blow dry air towards the western sides of continents.
• Cold ocean currents: Cold currents such as the Canary and California currents cool the lower air, create inversion, and prevent uplift and rain.
• Rain-shadow effect: Inland mountain ranges further block moist winds from reaching desert interiors.

Thus, the combined effect of global circulation, dry winds and cold currents makes western continental margins in the subtropics ideal for hot desert formation.