Maximize your crop yields by working with Mother Nature instead of against her. Wind machines work with nature to pull the warmer air down into the orchard or growing field to raise temperatures and save crops.
During the day, the sun heats the earth’s surface. The soil and trees become warmer than the air in contact with them and in turn heat the air. At night, the colder air settles to the ground and the warmer air rises forming an inversion.
Radiant frost occurs when a sudden drop in temperature due to heat radiation of the trees and soil causes the surrounding air to cool rapidly. The chilled air settles into the lowest areas in the orchard or growing field causing frost damage.
Wind machines pull the warm air from the inversion layer down into the crop zone, raising temperatures as much as six degrees, thus saving crops from being injured.
There are two types of weather conditions under which freezing temperatures occur, advective and radiational. In an advective freeze, most commonly occurring in extreme latitudes, cold air masses from the Arctic migrate south. These air masses are below freezing at the surface and become colder with elevation. Because this type of freeze occurs mostly in the winter in extreme latitudes, it is expected that crops are not planted or actively grown during the normal season for advective freezes. However, the arrival of an early fall or late spring advective freeze can be devastating to crops.
The second and most common type of weather condition that causes freezing temperatures is a radiational freeze. This type of freeze happens when a relatively cool, but dry air mass moves into an area. Even when afternoon temperatures are warm, after sunset radiational cooling at the earth’s surface causes temperatures in the lowest layers of the atmosphere to fall below freezing. While temperatures at the surface fall 30 degrees or more below the afternoon high, temperatures just a few hundred feet above the ground remain constant, forming an inversion.
Inversions are designated as either strong or weak, depending upon how much higher the night temperature is at the 50 to 60 foot elevation than at the 3 to 5 foot elevation. Wind machines are most effective when the inversion layer is 15 to 75 feet above the crop zone and when the temperature differential is from 3 to 7 degrees.
The popularity of wind machines has grown steadily since the early 1970s when rising fuel costs made oil-fired heaters an expensive option for frost damage control. Today, in extreme cold, heaters are used in combination with wind machines. Wind machines have proven to be an effective and cost-efficient means of protecting crops of all kinds against the damaging effects of spring frosts and winter freezes.