Frost-protection devices

For the purpose of this document, frost-protection devices are devices that are used to move air to reduce the risk of damage to crops from frost.

Frost-protection devices may either be permanent, consisting of a fan mounted tower, or helicopters may be used for frost control.

A radiation frost begins at ground level and gradually rises, and occurs when clear skies and calm winds result in there being no barrier to prevent heat loss from soil and plants. When the ground cools during radiation frosts an upper air layer, or inversion layer, will be warmer than the air that is closer to the ground.  

Wind machines and helicopters capitalise on the development of an inversion layer in a radiation frost. Their purpose is to circulate the warmer air down to crop level.

Heaters emit hot gases from the top of a stack which creates convective mixing in the crop area, tapping the important warm air source above the inversion layer.

Except for helicopter landing areas, the management of helicopter movements is typically outside the jurisdiction of local authorities, as they are controlled by Civil Aviation requirements. Requirements include, for instance, minimum safe operating height and weight limitations.

Photo of 4 bladed wind machine in a vineyard

Photo of 2 bladed wind machine in a vineyard.