Why do wind machines work best when a temperature inversion is present?

Wind machines are most effective during a temperature inversion because they rely on the presence of a warmer layer of air located just above the cooler surface air.12

During a nocturnal temperature inversion, the air temperature increases with height, creating a "ceiling" of warmer air above the ground. Wind machines function by mechanically mixing the atmosphere, which forces this warmer air downward to the surface. By breaking up the inversion and circulating the warmer air, the machines help raise the temperature at ground level, thereby protecting crops from frost damage.12

The effectiveness of these machines is directly proportional to the strength of the inversion; the greater the temperature difference between the surface and the air above, the more heat is available to be returned to the ground. Conversely, wind machines are ineffective against daytime freezes or advective frosts, where cold air is moving in horizontally rather than being trapped in a localized, stratified layer.2