All frost protection methods consist of using one or more of the following principles, according to USDA Agricultural Research Service irrigation ­specialist Dr. Robert Evans: Good site selection and proper siting of buildings, windbreaks, and fences so cold air drains away Mixing of the air, using wind machines or helicopters, to use heat stored in the atmosphere and to prevent ­stratification of cold air near the ground Direct heating of the air using heaters or undertree sprinkling with water Radiant heating occurs when heaters are glowing red Release of the latent heat of fusion from water applied to the canopy […]