Overhead irrigation system havc been used successfully to protect crops during radiation frosts*. The Emitters create a thin layer of water above the canopy. The water freezes and the latent heat (80 calories per 1 gram of water that freezes), released during the freezing process of the water protect the crop by keeping its temperature above freezing.
*Radiation frost (hoar frost) occurs on clear nights with little or no wind when the outgoing radiation is excessive and the air temperature is not necessarily at the freezing point.