Which atmospheric circulation pattern explains why deserts form near 30 degrees north and south latitude?

• A. Ferrel cell
• B. Hadley cell
• C. Polar cell
• D. Jet stream

Answer: (B)

Deserts near 30 degrees latitude arise from the Hadley cell circulation. At the equator, intense heating causes air to rise and produce heavy rain in the tropical zone. This air then moves poleward aloft, cools, and sinks around 30° north and south, creating high pressure at the surface. When air sinks, it warms and holds more moisture, so convection and cloud formation are suppressed, leading to very dry conditions. The resulting dry air at the surface contributes to arid climates typical of subtropical deserts. The surface winds in this system—trade winds blowing toward the equator from these subtropical highs—also help maintain the aridity. Other patterns like the Ferrel and Polar cells are part of the broader circulation but do not by themselves explain why deserts form specifically at these subtropical latitudes. The jet stream is a high-altitude boundary wind and doesn’t directly create the desert belts.