Climatic condition at a temperature below 0 °Celsius or 32 °Fahrenheit. In general, the air temperature is measured at the height of 1.25 metres above the ground; at this height, temperatures are always slightly higher than at ground level. In meteorology, frost at the height of the ground is called ground frost. Basically, a distinction is made between radiation fro st and adjective frost. Radiant frost occurs on dry clear nights with no wind, when the heat radiated by the ground or plant tissue escapes unhindered into the atmosphere due to the absence of clouds, fog or haze. The coldest (and heaviest) air sinks to the ground and collects on the surface and preferably in low-lying depressions. The adjective (meaning "added") frost is caused by the inflow of already cooled air from elsewhere. This can be from very distant areas such as through a long valley.
A certain degree of protection can already be achieved by taking appropriate measures when planting the vineyards. A slope from which the cold air drains away to lower areas (air drainage), as well as high forms of cultivation are of great advantage. Low-lying and flat areas are most at risk. Frost control in the vineyard is achieved by wind machines (or even by means of helicopters), which artificially induce mixing with the warmer air in the upper layers. Warming smoke stoves, large heaters and similar means are also used. Artificial irrigation can cause direct warming of the vines and the soil because heat is released when the water freezes or a thin layer of ice on parts of the plant also forms a protective coating.
In the northern hemisphere, frost in spring is generally referred to as late frost (also May frost in the month concerned) and in late summer/autumn as early frost. In the course of the annual vegetation cycle,...
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freier Autor und Weinberater (Fine, Vinum u.a.), Bad Krozingen