The earth absorbs heat from the sun during the day and releases it into the colder atmosphere at night. The heat loss is greatest just before dawn and this is usually when the maximum danger of frosts and frost damage occurs.







This nocturnal release of heat creates an 'inversion layer' of warmer air, which can be found from 10-50 metres above the ground.





During a radiation frost, a frost fan is used to draw down the warmer air in the inversion layer and blow it into the orchard or vineyard. The frost fan needs to blow as much air as it can, to the greatest distance possible. This will give the most economical coverage for the frost fan.



