What is snow? Where does the snow come from and what does it consist of?

Every time with the arrival of winter and snowfall, we are experiencing some emotional upsurge. A white blanket covering the city, dense forests and coppices, endless fields and broad rivers and bundled trees in fancifully shimmering clothes in the sun, will not leave indifferent neither the child nor the adult. As a child, we could sit by the window for hours and watch the snowflakes passing slowly circling past and quietly descending to the ground ... We often examined their structure, trying to find two identical, never ceasing to be surprised at the beauty and complexity of this magical splendor.

Snowy winter always fills the child's soul with a feeling of joy and inexplicable delight. Over time, when a child grows up, this feeling is dulled, but still somewhere in the depths of his soul everything freezes, and we enjoy the beauty, sleeping under a white veil of nature. Kids often ask their parents: "What is snow?" Adults usually respond in monosyllables, they say, it's frozen water. In this article we will try to understand not only the question of what snow is, but also examine its properties, both from the side of science and from poetry.

What do the encyclopedias say?

Dahl's dictionary answers the question about what snow is like, as follows: it's frozen water vapor, which falls like flakes, scraps of clouds; Loose ice, which replaces the winter rain. As you can see, the explanation is rather sparse. All-knowing Wikipedia is also short-lived, it says that snow is a form of atmospheric precipitation, which consists of small ice crystals. The encyclopedic dictionary informs the following: snow is a solid atmospheric precipitation, which consists of ice crystals differing in different forms; Snowflakes often have the form of hexagonal plates or stars; Drop out when the air temperature drops below zero degrees Celsius. It turns out that all dictionaries and encyclopedias say the same thing, but they do not bring clarity into the question of what snow is like. In this case, let us turn to the exact sciences.

Historical reference

Where does the snow come from? What does it consist of? What is its temperature? These and many other issues related to this natural phenomenon, scientists around the world are interested in a very long time. So, back in 1611, the astrologer and astronomer Kepler published a scientific treatise entitled "On hexagonal snowflakes". The author very pragmatically studied the crystals of snow in all the rigor of geometry. His work laid the foundation of such a science as theoretical crystallography. Another famous figure of the seventeenth century, the French mathematician and philosopher René Descartes, also studied the shape of snowflakes. They wrote in 1635 an etude, which was later included in the work "The experience of meteors." In the future, the question of what the snow consists of was considered by scientists all over the world countless times.

And do modern scientists study this phenomenon?

Today, even in kindergartens, kids are told that snowflakes have the shape of hexagons, that their pattern is unique and that there are no identical snowflakes. It would seem that everything is already known: at what temperature the snow melts, at what temperature it goes, and also much more. And yet, scientists have not lost interest in this miracle of nature and are still studying the formation of snowflakes. It turns out that they form around the so-called nuclei of crystallization, and, most interestingly, they can be the smallest particles of dust, soot, pollen of plants and even spores.

The quality of snow, sung by poets

A creak is an interesting effect. It can be heard only in exceptionally frosty weather. So, if there is a relatively warm day, then the snow cover will be silent. And quite differently he behaves during the real winter cold. People have noticed for a long time: the lower the temperature of snow and air, the higher the tone of the squeak. Scientists were able to find out that this effect occurs as a result of the crushing of microscopic ice crystals. When the temperature of the snow falls, these crystals become more fragile and hard, so they make a creaking sound, breaking under the wheels of cars and our feet. If you crush one such crystal, then we will not hear anything because of its small size. Such subtle sounds the human ear can not catch. But united, the crystals are able to create an exceptional musical background. Here this same creaking is sung by poets in their works.

Why is it snowing or raining?

Precipitation is associated with a violation of equilibrium (stability) of cloud masses, which consist of many elements of different structures and sizes. The more homogeneous this composition, the more stable the cloud, and, consequently, the longer it will not precipitate. In what form they fall to the ground, depends on the temperature of the air mass in the sublacial layer, as well as the height and structure of the cloud itself (as a rule, it is mixed, that is, it consists of droplets of chilled water and ice crystals). We will understand what follows from this. Falling out of the cloud, this mixture on the way to the surface of the planet passes through the similar masses. If the temperature is high enough then the ice crystals melt and turn into ordinary rain with a positive drop temperature. Sometimes, under condition of a small height of clouds, snowflakes can not have time to melt completely, in that case the snow falls out. This is why mixed precipitation may occur during the off-season. If the temperature of the sublimate mass is negative, then in this case there is simple snow.

Why does it sometimes snow in the summer and rain in the winter?

We dismantled at what temperature it is snowing, and at what temperature it is raining. However, sometimes incredible phenomena occur, for example, in the summer it may snow, and in the winter it may rain. What are the reasons for such cataclysms? Let's try to understand why this happens. Scientists explain this phenomenon by a deviation from the normal course of development of processes in the atmosphere. Thus, in winter, in the middle latitudes, masses of a very rich warm air can be caught moving from the basins of warm southern seas. As a result, thaws begin, which are manifested in the melting of fallen snow, as well as precipitation in the form of rain. In the summer, we can observe the reverse situation, that is, the cold air masses from the Arctic can break through to the south. When the warm front recedes, very intense cloudiness forms, on the dividing line of two air masses with different temperatures, the precipitation is very abundant. First in the form of rain, and then, with the subsequent cooling and under the condition of low clouds, in the form of simple or wet snow. In the southern regions, this happens rarely, while the temperature on the surface of the earth remains positive.

Snow rolls - what is this anomaly?

The first time you see this miracle of nature, you decide that this is the creation of the hands of man. In fact, such paths or rolls are turned by nature itself. This is a fairly rare meteorological phenomenon. Snow rolls create a wind that rolls snow until it gains in weight and size. Usually such figures have the shape of cylinders, but there are exceptions. This phenomenon can be observed only in regions with a strong gusty wind, light wet snow and only in open terrain. Snow rolls roll over the steppe like empty barrels. Their size can reach 30 cm in diameter and 30 cm in width. In fact, hundreds of separate rolls can appear simultaneously on a snow-covered field. Behind each of them there is a trace - a peculiar path, which indicates the trajectory of the path traveled. Snow rolls are often formed during the passage of winter storms, when the wind is strong and the snow is fresh. The air temperature should be close to zero.

The process of forming snow rolls

This is as follows: the surface of the earth should be covered with a ground ice cake or old caked snow, in which case the falling snowflakes with the underlying layer have a weak grip. The lower layer must have a negative temperature, and the upper layer must be positive (slightly above zero degrees). Then fresh snow will have a high "stickiness". The optimum temperature is minus two degrees for the lower layer and plus two for the upper layer. Gusty wind should have a speed of more than 12 m / s. The formation of the roll will begin when the wind "digs out" a piece of snow. Further small lumps are formed, rolling along the field under the influence of the wind, forming an ever larger layer of wet snow with each meter. When the roll becomes too heavy, it stops. So its size directly depends on the speed of the air flow.

Interesting facts about snow

1. A snowflake is 95% air. Due to this, it falls very slowly, at a speed of 0.9 km / h.

2. The white color of the snow is explained by the presence of air in its structure. In this case, the rays of light are reflected from the boundary of the ice crystal with air and are scattered.

3. In the history of recorded cases of falling colored snow. So, in 1969 in Switzerland black snow fell, and in 1955 in California - green.

4. In the high mountains and Antarctica, you can find a snow cover of pink, red, purple, yellowish-brown flowers. This is promoted by the creature - Chlamydomonas Snow, which lives in the snow.

5. When a snowflake falls into water, it emits a strong high-frequency sound. The human ear can not catch it, but fish can, and, according to scientists, they do not like it much.

6. Under normal conditions, snow melts at a temperature of zero degrees Celsius. However, if it hits the sunlight, it can evaporate even at subzero temperatures, bypassing the liquid form.

7. In winter, snow reflects up to 90% of the sun's rays from the earth's surface, thus preventing it from warming up.

8. In 1987, Fort-Coe (USA) recorded the largest snowflake in the world. Its diameter was 38 cm.

Finally

So we dismantled this weather phenomenon, which is so sparingly described encyclopedias and dictionaries. Now we know at what temperature the snow melts, at what time it goes, how, when and why there are snow rolls and much more, associated with this beautiful messenger and the companion of winter.