Why Do Deserts Get So Cold at Night?

Temperatures drop steeply in deserts at night because the dry air does not hold down the energy absorbed by the soil during the day as light and radiated upward as heat. This phenomenon creates an energy deficit on the desert's surface and causes "radiational cooling."

  1. Dry Heat, Dry Cold

    • More extreme temperatures occur in a desert. Indeed, these dry regions frequently lose more moisture as a result of evaporation than they gain in annual rainfall, according to National Geographic. There is little moisture in the soil and even less in the air to form clouds and moderate extremes in temperatures.

    Bright Shortwave, Dark Longwave

    • During the day, the sun pours down "shortwave" radiation -- visible light. The soil, even in a desert, reflects back mostly "longwave" radiation -- heat that is not visible to human beings. Longwave radiation continues to rise even when shortwave radiation stops at sunset.

    Imbalance of Power

    • When an area of the Earth's surface radiates more longwave energy up than the sun sends down in shortwave form, the energy deficit at the surface results in radiational cooling.

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