Major hot deserts in northern hemisphere are located between 20-30° N latitudes and on the western side of…

Question

Major hot deserts in northern hemisphere are located between 20-30° N latitudes and on the western side of the continents. Why?

Ghissu Editorial · Accepted Answer

Hot deserts lie at 20-30°N because the sinking, adiabatically warming air of the subtropical high suppresses rain, and on western margins because offshore trade winds and cold currents keep moisture away. The Canary and California currents, for instance, chill coastal air into fog-bearing but rainless inversions.

**Introduction**

The Sahara, Arabian, Thar and Sonoran deserts crowd into one narrow band because latitude decides where air sinks and dries, and continental position decides whether moist ocean winds can reach the land.

**Why Aridity Concentrates Between 20° and 30°N**

1. **Subtropical high pressure**: The Hadley cell's descending limb sinks near 25-30°N, and the sinking air warms adiabatically, so relative humidity falls and clouds cannot form.
2. **Capped atmosphere**: Subsidence builds a trade-wind inversion that lids rising air, suppressing the convection needed for rain.
3. **Outside both rain belts**: The band lies beyond the ITCZ's convective rain and the westerlies' cyclones, and cloudless skies under a high sun let insolation scorch the surface by day.

**Why the Western Side of Continents**

SKETCH: comparison | Western vs Eastern Margins, 20-30°N
a: Western margin
b: Eastern margin
- Offshore trades :: Onshore trades
- Cold current :: Warm current
- Inversion, fog :: Unstable moist air
- Hot desert :: Humid subtropical

1. **Offshore trade winds**: The north-east trades blow from east to west, watering eastern coasts like south China and Florida but reaching western margins only after crossing dry land.
2. **Cold ocean currents**: The Canary and California currents chill the air above them, creating an inversion that brings coastal fog but almost no rain.
3. **Relief barriers**: The Sierra Nevada shadows the Mojave, and the Aravallis, parallel to the monsoon winds, leave the Thar dry.

**Conclusion**

Hot deserts form where the sinking air of the subtropical high meets offshore trades and cold currents, while eastern margins at the same latitudes stay humid. The mirror-image Atacama and Namib, framed by the Humboldt and Benguela currents, confirm that planetary circulation, not latitude alone, draws this desert belt.

Major hot deserts in northern hemisphere are located between 20-30° N latitudes and on the western side of the continents. Why?

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