Precipitation sum

Atmospheric precipitation consists of water drops or ice crystals, which are too heavy to stay suspended in a cloud and fall on the ground in various shapes, of which the most common are rain and snow, however, there are a lot more types of precipitation. Main types of precipitations, concerning genesis, are frontal and convectional precipitations. Frontal precipitations occur on areas where air masses of different properties (known as fronts) meet and are emerged by cooling the humid air mass down. Most often these are long-lasting, moderate-intense precipitations, which appear on a large area simultaneously. Convectional precipitations occur when the humid air mass warms up from the ground and floats up rapidly and steam contained in the air condenses, creating Cumulonimbus clouds, which often reach the upper border of troposphere. Convectional precipitations are usually intermittent, very intensive and on a small range.

Precipitation height is expressed in mm or l/m2 and it is usually measured by Hellmann rain gauge and their variability in time- by pluviograph. The highest precipitation sums in Lower Silesia occur in summer, the smallest in winter and the annual precipitation sum equals averagely from 550 mm in the lowland to 1000 in the Sudetes

Elaborated by K. Wałaszek