What Is Compressional Heating?

Compressional heating occurs when an air mass is squeezed into a smaller area than before.

This can occur when air sinks, either down a mountain or from upper portions of the lower atmosphere.

Compressional Heating Due To Mountains

Compressional heating often occurs when air masses move over mountainous terrain. The mountains force the air to rise on one side, causing cooling and precipitation, and to sink on the other side, causing heating and a decrease in moisture.

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As a result, deserts are very common on the leeward side of a mountain range, or the side in which air sinks. Examples of deserts formed from mountains include the Sonoran and Mojave deserts in Arizona and California respectively.

Heat Domes

Another example of compressional heating caused by sinking air is heat domes during the summer months. During heat dome events, high pressure at the upper levels of the lower atmosphere forces air to sink, drying and heating up in the process. An excellent example of this phenomenon is the historic June 2021 Pacific Northwest Heatwave in which temperatures over 110 degrees were recorded in many cities.

Cold Fronts

Compressional heating also may occur preceding a cold front. This occurs when the warm air ahead of the cold front is compressed just before the passage of the cold front. As a result, temperatures may be a few degrees warmer just ahead of a cold front compared to areas well within the warmer air mass. Compressional heating can occur anytime of year but can cause drastic temperature swings, particularly during the winter months.

Hayden Marshall is a meteorologist intern and First-Year-Master’s Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.