Peach growers use a 4.5-meter fan to push warm air down on a freezing night. Texas wind farm did the same for miles around

On a freezing night, peach growers face a particularly damaging enemy: cold air pooling near the ground and threatening the trees’ blossoms. Their response can involve a 4.5-meter fan mounted on a tower, turning upper-layer air downward toward the crop.

The equipment does not generate heat. It takes advantage of a temperature inversion, a weather pattern that often forms on clear, calm nights. The ground loses heat after sunset, cooling the air closest to it. Because that air is heavier, it remains near the surface while a warmer layer stays above.

Agricultural fans are designed to break up that arrangement. Some have blades about 4.5 meters across and sit on towers roughly nine meters high. By reaching the warmer air overhead and mixing the layers, they can raise temperatures around the trees by several degrees and reduce the risk to new growth during a critical night.

The same basic process appeared in an unexpected setting: wind farms in Texas. Satellite measurements detected higher temperatures near turbines during some winter nights. The turbines’ enormous rotors operate in the same upper air layers that farmers try to reach with their fans.

One measurement over a Texas wind farm found ground temperatures 4 to 7 degrees Fahrenheit higher during a January night across several kilometers downwind. The readings do not mean the turbines created heat. Their blades mixed the air and could move some of the warmth held above down toward the surface, increasing measured ground-level temperatures without increasing the total amount of thermal energy.