Snow SVG is a form of precipitation consisting of small ice crystals. It refers to the cover sediments falling on the earth’s surface.
Snow SVG forms when microscopic droplets of water in the clouds are attracted to dust particles and freeze. The resulting ice crystals, which do not exceed 0.1 mm in diameter at first, fall down and grow as a result of condensation of moisture from the air. Six-pointed crystalline forms are formed. Because of the structure of the water molecules between the crystal beams, angles of only 60° and 120° are possible. The basic water crystal has the shape of a regular hexagon in the plane. At the tops of this hexagon then precipitated new crystals, on them – new, and so a variety of shapes of snowflake stars are obtained.
At high temperatures, the crystals repeatedly move vertically in the atmosphere, partially melting and crystallizing again. As a result, the regularity of the crystals is disturbed and mixed shapes are formed. Crystallization of all six rays takes place at the same time, in almost identical conditions, and therefore the shape of the snowflake rays is equally identical.
White snow is created by the air enclosed in the snowflake. Light of various lengths is emitted on the boundary surfaces between the ice crystals and the air and dissipates, but depending on the chemical composition of the snow can acquire different colors. Snowflakes consist of 95% air, which results in a low density (100-400 kg/m³) and a relatively slow falling speed (0.9 km/h).
The largest snowflakes were observed on 28 January 1887 during a snowfall in Fort Kyow, Montana, USA; one of them was 15 x 8 inches (about 38 x 20 cm) in size. In Bratsk in 1971, snowflakes measuring 20 x 30 cm were recorded. Usually, snowflakes have about 5 mm in diameter with a mass of about 0.004 g.
There is such a variety of snowflakes that it is usually believed that there are no two identical snowflakes. For example, Kenneth Liebrecht, the author of the largest and most diverse collection of snowflakes, says: “All snowflakes are different, and their placement in groups (classification) is largely a matter of personal preferences. Simple snowflakes, for example, prisms formed at low humidity, may look the same, although at the molecular level they differ. Complex starry snowflakes have a unique, eye-catching geometric shape. And variants of such forms, according to the physicist John Nelson from the University of Rizumeikan (Jap.) in Kyoto, more than atoms in the observed universe.
Snow SVG as a weather phenomenon
Snow is one of the essential attributes of winter. Despite the fact that low winter temperatures are possible and there is no snow, one of the main conditions of climatic winter is the presence of stable (permanent) snow cover, which lies throughout the winter continuously or at short intervals.
The equatorial and subequatorial climatic zones do not have such a weather phenomenon as snow. In the tropical belt, snow is extremely rare (once every few decades) and can fall on the border with the subtropical belt. In the subtropics on the border with the temperate snow belt, snow is a regular phenomenon in winter.
Snow SVG is characterized by a variety of parameters: the thickness of the cover, the amount of water in it, crumbliness, etc. In addition to typical snowfalls, there are special snowfalls associated with extratropical cyclones, lakes and mountainous terrain.
Extratropical cyclones typical of Western Europe, Canada and Greenland in the Northern Hemisphere can create extreme conditions when there is heavy rainfall and heavy snow with winds exceeding 119 km/h. The deposition belt, which is linked to their warm front, is often extensive, caused by weak upward air movement over the frontal boundary; moisture condenses when it cools down and creates precipitation, forming a strip of layered rain clouds. In the cold sector, towards the pole and west of the centre of the cyclone, small or medium snowfall bands are usually between 32 and 80 km wide. These bands are associated with areas of cyclone frontogenesis, or temperature contrast zones.
Frequent cold air coming in with cyclones can lead to the effects of snowfall bands over large water bodies: large lakes efficiently accumulate heat, resulting in significant temperature differences (more than 13°C) between the water surface and the air above, due to this difference in temperature, heat and moisture move upwards, compacting in vertically oriented clouds that produce snow. The higher the temperature drop with height, the thicker the clouds and the more intense the snowfall.
In mountainous areas, heavy snowfalls occur when the air is forced to rise into the mountains and cool down, giving off excess atmospheric moisture that falls out in the cold conditions of highlands on their windward slopes in the form of snow. Due to the mountainous terrain, the prediction of heavy snowfalls remains a serious problem here.