A term commonly used in meteorology to describe water that falls to earth either in liquid form from rain or thunderstorms and/or in solid form from hail, sleet, crumble or snow from clouds, or is deposited as surface precipitation directly on objects such as the earth's surface by condensation (as in dew) or resublimation, i.e. the direct transition of a substance from a gaseous to a solid state of aggregation (as in frost). The amount of precipitation required in viticulture also depends on the respective soil conditions, such as water abstraction and water storage capacity. The annual lower limit is at least 200 mm of precipitation, for quality viticulture an average of 500 mm is required, in warmer climates with high evaporation 750 mm.
There is no upper limit, provided the soil conditions are suitable, because even more than 1,500 mm within a short time can be tolerated, especially in hot areas. However, the timing of precipitation in the vegetation cycle can be critical. Heavy rain shortly before the grape harvest, especially after a long period of drought, can cause the grapes to swell and dilute the sugar, acid and aroma content. Within the EU, artificial irrigation is regulated differently in the different countries, mostly by wine law. The amount of precipitation is one of the criteria for so-called wine-growing eligibility.
Thunderstorm: From Felix Mittermeier on Pixabay
Rain: From Krzysztof Pluta on Pixabay
Hail: From Darkone - Photographed by myself, CC BY-SA 2.0, Link
Sleet: From Hilde Stockmann on Pixabay
Raindrop: From TheSkunk - Own work, CC BY-SA 3.0, Link
edited by Norbert F. J. Tischelmayer - June 2019