Each time with the arrival of winter and snowfall, we experience some kind of emotional outburst. The white cover that covered the city, dense forests and copses, endless fields and wide rivers and wrapped trees in fancy clothes flickering in the sun, will not leave indifferent either a child or an adult. As a child, we could sit for hours at the window and watch how, slowly circling, snowflakes fly by and quietly fall to the ground ... We often looked at their structure, trying to find two identical ones, without ceasing to wonder at the beauty and complexity of this magical splendor.
Snowy winter always fills the soul of children with a sense of joy and inexplicable delight. Over time, when the child grows up, this feeling becomes dull, but still somewhere in the depths of our souls everything freezes, and we enjoy the beauty that sleeps under the white veil of nature. Kids often ask their parents: "What is snow?" Adults usually answer in monosyllables, they say, this is frozen water. In our article, we will try to understand not only the question of what snow is, but also consider its properties, both from the side of science and from the side of poetry.
What do encyclopedias say?
Dahl's dictionary answers the question of what snow is, as follows: these are frozen water vapor that fall in the form of flakes, shreds from clouds; loose ice, which replaces the winter rain. As you can see, the explanation is rather mean. The omniscient Wikipedia is also laconic, it says that snow is a form of precipitation that consists of small ice crystals. The encyclopedic dictionary reports the following: snow is a solid precipitation that consists of ice crystals of different shapes; snowflakes most 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 the dictionaries and encyclopedias say the same thing, but they do not bring clarity to the question of what snow is. In this case, we turn to the exact sciences.
History reference
Where does the snow come from? What does it consist of? What is its temperature? Scientists from all over the world have been interested in these and many other issues related to this natural phenomenon for a very long time. So, back in 1611, an astrologer and astronomer Kepler published a scientific treatise, entitled "On Hexagonal Snowflakes." The author has very pragmatically studied snow crystals in all severity of geometry. His work formed the basis of such a science as theoretical crystallography. Another famous seventeenth-century figure, the French mathematician and philosopher Rene Descartes, also studied the shape of snowflakes. He wrote a study in 1635, which was subsequently included in the work “Experience on Meteors”. In the future, the question of what snow consists of has been considered by scientists around the world countless times.
Are modern scientists studying this phenomenon?
Today, even in kindergartens, kids are told that the snowflakes are in the form 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 it is snowing, and also much more. Nevertheless, scientists have not lost interest in this miracle of nature and are still studying the processes of snowflake formation. It turns out that they are formed around the so-called crystallization nuclei, and, most interestingly, they can be the smallest particles of dust, soot, plant pollen and even spores.
The quality of snow sung by poets
Squeaking is an interesting effect. It can be heard only in extremely frosty weather. So, if there is a relatively warm day, then the snow cover will be silent. And very differently, he behaves during a real winter cold. People have long noticed: the lower the temperature of snow and air, the higher the tone of the creak. Scientists were able to find out that this effect occurs as a result of crushing of microscopic ice crystals. When the snow temperature drops, these crystals become more fragile and solid, so they make a creaking sound, breaking under the wheels of cars and our feet. If one such crystal is crushed, then we will not hear anything due to its small size. The human ear cannot catch such subtle sounds. But united, the crystals are able to create an exceptional musical background. This is the same creak and poets sing in their works.
Why is it snowing or raining?
Precipitation is associated with the imbalance (stability) of cloud masses, which consist of many elements of different structures and sizes. The more uniform this composition, the more stable the cloud, and, accordingly, the longer it will not produce precipitation. The form in which they fall to the ground depends on the temperature of the air mass in the cloudless layer, as well as the height and structure of the cloud itself (as a rule, it is mixed, that is, consists of drops of chilled water and ice crystals). Let's figure out what follows from this. Falling out of the cloud, this mixture, on its way to the surface of the planet, passes through cloudless masses. If the temperature is high enough, the ice crystals melt and turn into ordinary rain with a positive temperature of the drops. Sometimes, provided the clouds are small in height, the snowflakes may not have time to completely melt, in which case wet snow will fall. That is why mixed precipitation may occur during off-season periods. If the temperature of the sub-cloud mass is negative, then in this case there is simple snow.
Why does snow sometimes fall in summer and rain in winter?
We figured out at what temperature it snows and at what temperature it rains. However, sometimes unbelievable events happen, for example, snow may fall in the summer and rain in the winter. What explains such disasters? Let's try to understand why this is happening. Scientists explain this phenomenon by a deviation from the normal course of development of processes in the atmosphere. So, in winter, masses of very rich in moisture warm air moving from basins of the warm southern seas can get to mid-latitudes. As a result, thaws begin, which are manifested in the melting of the fallen snow, as well as precipitation in the form of rain. In the summer, we can observe the opposite situation, that is, cold air masses from the Arctic can erupt to the south. During the retreat of the warm front, very powerful clouds form; on the dividing line of two air masses with different temperatures, precipitation is very plentiful. First, in the form of rain, and then, with subsequent cooling and subject to low cloud cover, in the form of simple or wet snow. In the southern regions, this rarely happens, while the temperature on the surface of the earth remains positive.
Snow rolls - what is this anomaly?
For the first time you see this miracle of nature, you decide that this is the work of man. In fact, such paths or rolls are twisted by nature itself. This is a fairly rare meteorological phenomenon. Snow rolls are created by the wind rolling snow until it gains weight and size. Typically, these figures are in the form of cylinders, but there are exceptions. This phenomenon can be observed only in regions with strong gusty winds, light wet snow and only in open areas. Snow rolls roll across the steppe like empty barrels. Their size can reach 30 cm in diameter and 30 cm in width. In fact, on a snowy field hundreds of separate rolls can occur simultaneously. Each of them leaves a trace - a kind of path that indicates the trajectory of the path traveled. Snow rolls are often formed during 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 happens as follows: the surface of the earth must be covered with a crushed ice crust, or with old packed snow, in which case the falling snowflakes with the underlying layer have poor adhesion. In this case, the lower layer should have a negative temperature, and the upper one should be positive (slightly above zero degrees). Then fresh snow will have a high “stickiness”. The optimum temperature is minus two degrees for the bottom layer and plus two for the top. Gusty wind should have a speed of more than 12 m / s. Roll formation will begin when the wind “digs out” a piece of snow. Then small lumps are formed, rolling along the field under the influence of the wind, growing with each meter an ever-increasing layer of wet snow. When the roll becomes too heavy, it stops. So its size directly depends on the air flow rate.
Interesting facts about snow
1. Snowflake is 95% air. Due to this, it falls very slowly, at a speed of 0.9 km / h.
2. The white color of snow is explained by the presence of air in its structure. In this case, light rays are reflected from the boundary of the ice crystal with air and scattered.
3. In the history of recorded cases of colored snow. So, in 1969, black snow fell in Switzerland, and green in California in 1955.
4. In the high mountains and Antarctica you can find snow cover of pink, red, purple, yellowish-brown colors. This is facilitated by the creature - snow chlamydomonas, which lives in the snow.
5. When a snowflake falls into the water, it emits a strong high-frequency sound. The human ear is not able to catch it, but fish can, and, according to scientists, they really do not like it.
6. Under normal conditions, snow melts at a temperature of zero degrees Celsius. However, when it is exposed to sunlight, it can also evaporate at sub-zero temperatures, while bypassing the liquid form.
7. In winter, snow reflects from the earth's surface up to 90% of the sun's rays, thereby preventing it from warming up.
8. In 1987, Fort Coy (USA) recorded the largest snowflake in the world. Its diameter was 38 cm.
Finally
So we sorted out this weather phenomenon, which is so sparingly described by encyclopedias and dictionaries. Now we know at what temperature the snow melts, at what it is, how, when and why snow rolls arise and much more associated with this beautiful messenger and winter companion.