The assertion, familiar to every schoolchild, that no two snowflakes are alike, has been repeatedly questioned. But the unique research of the Californian University of Technology were able to put the finishing touches on this truly New Year's question.
Snow forms when microscopic drops Water in clouds is attracted to dust particles and freezes.
The ice crystals that appear, initially not exceeding 0.1 mm in diameter, fall down and grow as a result of condensation of moisture from the air on them. This produces six-pointed crystalline forms.
Due to the structure of water molecules, angles of only 60° and 120° are possible between the rays of the crystal. The main water crystal has a plane shape regular hexagon. New crystals are then deposited on the vertices of such a hexagon, new crystals are deposited on them, and so the result is various forms snowflake stars.
University of California physics professor Kenneth Libbrecht unveiled the results of years of research on his scientific group. "If you see two identical snowflakes– they still differ!” - says the professor.
Libbrecht proved that in the composition of snow molecules, for approximately every five hundred oxygen atoms with a mass of 16 g/mol, there is one atom with a mass of 18 g/mol.
The structure of the bonds of a molecule with such an atom is such that it suggests an innumerable number of options for connections within the crystal lattice.
In other words, if two snowflakes really look the same, then their identity still needs to be verified at the microscopic level.
Studying the properties of snow (and, in particular, snowflakes) is not child's play. Knowledge about the nature of snow and snow clouds is very important when studying climate change.
Let's see how this can be arranged.
One water molecule is one oxygen atom and two hydrogen atoms connected to each other. When frozen water molecules bind together, each molecule gets four other tethered molecules nearby: one at each of the tetrahedral vertices above each individual molecule. This causes the water molecules to form a lattice shape: hexagonal (or hexagonal) crystal lattice. But large "cubes" of ice, like those found in quartz deposits, are extremely rare. When you look into the smallest scales and configurations, you find that the top and bottom planes of this lattice are packed and connected very tightly: you have "flat edges" on two sides. The molecules on the remaining sides are more open, and additional water molecules bind to them more randomly. In particular, hexagonal angles have the most weak ties, so we observe sixfold symmetry in crystal growth.
and the growth of a snowflake, a particular configuration of an ice crystal
New structures then grow in the same symmetrical patterns, increasing in hexagonal asymmetries once they reach a certain size. Large, complex snow crystals have hundreds of easily distinguishable features when viewed under a microscope. Hundreds of features among the approximately 10 19 water molecules that make up the average snowflake, according to Charles Knight of National Center atmospheric research. For each of these functions there are millions of possible places where new branches can form. How many such new features can a snowflake form without becoming just another of many?
Every year, approximately 10 15 (quadrillion) cubic meters of snow fall on the ground worldwide, and each cubic meter contains about several billion (10 9) individual snowflakes. Since the Earth has existed for about 4.5 billion years, 10 34 snowflakes have fallen on the planet throughout history. And do you know, from a statistical point of view, how many separate, unique, symmetrical branching features could a snowflake have and expect to have a twin at a certain point in Earth's history? Just five. Whereas real, large, natural snowflakes usually have hundreds of them.
Even at the level of one millimeter in a snowflake you can see imperfections that are difficult to duplicate
And only at the most mundane level can you mistakenly see two identical snowflakes. And if you're ready to get down on molecular level, the situation will become much worse. Typically, oxygen has 8 protons and 8 neutrons, while a hydrogen atom has 1 proton and 0 neutrons. But 1 out of 500 oxygen atoms has 10 neutrons, 1 out of 5000 hydrogen atoms has 1 neutron, not 0. Even if you form perfect hexagonal snow crystals, and in the entire history of planet Earth 10 34 snow crystals have been counted, it will be enough to drop to the size several thousand molecules (less than the length visible light) to find a unique structure that the planet has never seen before.
But if you ignore the atomic and molecular differences and abandon the "natural", you have a chance. Snowflake researcher Kenneth Libbrecht of California Institute of Technology has developed a technique for creating artificial “identical twins” of snowflakes and photographs them using a special microscope called the SnowMaster 9000.
By growing them side by side in the laboratory, he showed that it was possible to create two snowflakes that were indistinguishable.
Two almost identical snowflakes grown in a Caltech laboratory
Almost. They will be indistinguishable to a person looking with their own eyes through a microscope, but they will not be identical in truth. Like identical twins, they will have many differences: they will have different places bundles of molecules, different properties branches, and the larger they are, the stronger these differences. That's why these snowflakes are very small, but the microscope is powerful: they are more similar when they are less complex.
Two almost identical snowflakes grown in a laboratory at Caltech
Nevertheless, many snowflakes are similar to each other. But if you are looking for truly identical snowflakes on a structural, molecular or atomic level, nature will never give you this. This number of possibilities is great not only for the history of the Earth, but also for the history of the Universe. If you want to know how many planets you need to get two identical snowflakes over the 13.8 billion year history of the universe, the answer is on the order of 10 100000000000000000000000. Considering that there are only 10 80 atoms in the observable Universe, this is extremely unlikely. So yes, snowflakes are truly unique. And that's putting it mildly.
Scientists identify two options for the formation of snow crystals. In the first case, water vapor carried by the wind to a very high altitude, where the temperature is about 40 ° C, can suddenly freeze, forming ice crystals. In the lower layer of clouds, where water freezes more slowly, a crystal is created around a small speck of dust or soil particle. This crystal, of which there are from 2 to 200 in one snowflake, has the shape of a hexagon, so most snowflakes are a six-pointed star.
“Land of Snows” - this is the poetic name its inhabitants came up with for Tibet.
The shape of a snowflake depends on many factors: surrounding temperature, humidity, pressure. However, there are 7 main types of crystals: plates (if the temperature in the cloud is from -3 to 0 ° C), star-shaped crystals, columns (from -8 to -5 ° C), needles, spatial dendrites, columns with a tip and irregular shapes. It is noteworthy that if a snowflake rotates as it falls, then its shape will be perfectly symmetrical, but if it falls sideways or in some other way, then it will not.
Ice crystals are hexagonal: they cannot be connected by an angle - only by an edge. Therefore, the rays from a snowflake always grow in six directions, and the branching from the ray can only extend at an angle of 60 or 120°.
Since 2012, “World Snow Day” has been celebrated on the penultimate Sunday of January. This was initiated by the International Ski Federation.
Snowflakes appear white because of the air they contain: light different frequencies is displayed on the edges between the crystals and is scattered. The size of an ordinary snowflake is about 5 mm in diameter, and its mass is 0.004 g.
When scoring the film “Alexander Nevsky,” the creaking of snow was obtained by squeezing mixed sugar and salt.
It is believed that no two snowflakes are alike. This was first proven in 1885, when American farmer Wilson Bentley took the first successful photograph of a snowflake under a microscope. He devoted 46 years to this and took more than 5,000 photographs, on the basis of which the theory was confirmed.
Project work ARE THERE SNOWFLAKES THE SAME Completed by: Makar Zhikharev, 3rd grade, Lyceum No. 179, St. Petersburg. Head: Agafonova S.V.
During a snowfall, we rarely think that ordinary snowflakes can demonstrate the amazing complexity of their structure, regularity and variety of shapes. This is clearly visible even with the naked eye, but if we examine the snowflakes through a microscope, new and very surprising details will be revealed to us.
PLAN RESEARCH OBJECTIVE: to study snowflakes, how amazing phenomenon nature. RESEARCH OBJECTIVES: observation of snowflakes in nature; studying the formation of snowflakes; identifying the diversity of snowflake shapes and the causes of snow creaking; experimentally observe the formation of snowflakes; identify students’ knowledge about snowflakes;
HYPOTHESIS If water is formed when snowflakes melt, then snowflakes appear from water. If there are so many snowflakes, then in nature there must be a large number of identical snowflakes.
Subject of study SNOWFLAKES SNOW
What is a SNOWFLAKE A snowflake is a complex symmetrical structure consisting of ice crystals. Snow forms when microscopic water droplets in clouds are attracted to dust particles and freeze. The ice crystals that appear fall down and grow as a result of condensation of moisture from the air on them. This produces six-pointed crystalline forms. And the snowflake is sent to the ground as a six-pointed star. ;
STUDYING THE SNOWFLAKE Wilson A. Bentley Professor Libbrecht
STUDYING SNOWFLAKES
EXPERIMENT 1 I froze water droplets, but the snowflakes didn’t turn out. This means that snow does not appear from water droplets. Droplets of water can become hailstones, lumps of ice, but not snowflakes.
EXPERIMENT 2 In the snow, I went outside and placed my mitten under the snow. Several snowflakes fell on her. I began to examine them with a magnifying glass. Nezhinki can only be seen clearly when they fall into the palm of your hand. Under the influence of even a small force, they break, which means snowflakes are very fragile.
What are snowflakes?
INTERVIEW I conducted an interview among 25 students of grade 3-A at school No. 619, where my friend studies. According to the interview results, 20 out of 25 guys claim that a snowflake consists of water; - 24 out of 25 guys claim that there are identical snowflakes;
MYTH ABOUT THE SAME SNOWFLAKES
INTERESTING FACTS ABOUT snowflakes
CONCLUSIONS Working on the topic, I achieved my goal and learned a lot about snowflakes. In the process of study and research, I solved the problems I set. Unfortunately, my hypotheses were not confirmed. Because of this, we now know exactly how snowflakes are formed and what they are like.
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