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Selective Inverted Sink
From Wikipedia, the free encyclopedia
The Selective Inverted Sink, or SIS, is a device which protects farmed plants by reducing the likelihood of frost.
The technology which ultimately came to be called the "Selective Inverted Sink" was developed and patented in Uruguay by Rafael Guarga in the 1990s.
Because cold air is more dense than warm air, in calm weather, dense, cold air can pool at ground level. This phenomenon is known as surface temperature inversion, and can be a significant danger to crops that are sensitive to frost. The Selective Inverted Sink is designed to disperse this low-lying cold air, displacing and mixing it with warmer air above the treetops of a typical orchard. The SIS consists of a chimney-like structure, housing a fan propellor, and some kind of motor to turn the propellor. The chimney sits close to the ground, and has vents in its base so that cold air can enter from all sides. The fan blows the cold air upward, creating a suction pressure below, which in turn allows more of the dense, cold air to enter the vents and the chimney. The SIS is far more efficient than heaters, still widely used for the same purpose of discouraging frost.
