What is "smudge pot"

n. 1 An oil-burning device used to prevent frost on fruit trees. 2 A pot of tar and oil burned to produce thick noxious smoke to discourage pests.

A smudge pot (also known as a choofa or orchard heater) is an oil-burning device used to prevent frost on fruit trees. Usually a smudge pot has a large round base with a chimney coming out of the middle of the base. The smudge pot is placed between trees in an orchard. The burning oil creates some heat, but more importantly, a large amount of smoke, particulates, carbon dioxide, and water vapor. This deliberate smog forms a "blanket" that blocks infrared light, thereby preventing radiative cooling that would otherwise cause or worsen frost. (Low clouds can have a similar "infrared blanket" effect, which is why cloudy nights tend to be warmer than clear-sky nights.)