Heat Dome: Subsiding Ridge, Mixed-Layer Warming, and the Soil-Drying Feedback

What is a Heat Dome?

A heat dome occurs when a persistent high-pressure system, often associated with a subsiding air mass, causes the atmosphere to sink. As this air descends, it warms and can lead to unusually hot temperatures at the surface.

This phenomenon is particularly significant in summer months when the sun’s radiation heats the Earth's surface, causing warm air to rise and cooler air to move in from higher altitudes.

Subsidence Warming

When air descends due to a high-pressure system, it compresses and warms. This process is known as adiabatic heating, where the temperature of the air increases without exchanging heat with its surroundings.

The warming effect can be substantial; for example, an air mass that descends 10,000 meters can warm by up to 25°C due to compression and adiabatic heating.

Mixed-Layer Warming

The mixed layer is the uppermost part of the atmosphere that mixes with the surface, typically extending down to a few hundred meters. In a heat dome, this layer warms as it receives more solar radiation and is less turbulent due to subsidence.

This warming can lead to a shallower mixed layer, reducing mixing between the air near the ground and the upper layers of the atmosphere.

Soil-Drying Feedback

As the temperature rises in the heat dome, evaporation from soil moisture increases. However, this process can lead to a feedback loop where drying out the soil further reduces its ability to retain water and cool the surface.

This feedback loop can exacerbate the warming effect, creating a self-reinforcing cycle that intensifies the heat dome.

Frequently asked questions

Try it live

Everything above runs in your browser — open Heat Dome: Subsiding Ridge, Mixed-Layer Warming and the Soil-Drying Feedback and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.