Effectiveness of wind machines: Frost protection by ramjet or conventional wind machines in deciduous orchards depends on the strength of the inversion
California Agriculture 11(8):7-9.
Published August 01, 1957
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When the atmosphere 40' to 50' above ground is 13°F or more warmer than it is a few feet above the soil surface, the temperature inversion condition—in frost protection research—is considered to be strong. When the temperature difference is less than about 5°F the inversion is considered weak. The weak inversions usually found in the deciduous orchards on the floor of the Sacramento Valley appear to limit the usefulness of wind machines for frost protection unless additional heat is supplied from orchard heaters.