Modern double-glazed windows made impossible favourite entertainment of the childhood. On glasses in frosty day entertaining patterns ceased to appear. Progress conflicted to beauty.
About cold and air
In air there are always moisture vapors. If you are not in the Sahara Desert, of course. There with water the situation is more intense. When air is cooled, surplus of moisture is distinguished from it as dew. So occurs in the fresh summer morning after hot day. In a day, air is sated with evaporations from the earth, the rivers and lakes. And at daybreak temperature falls. The grass becomes covered by the smallest droplets, the playing all colors of the rainbow in the light of a rising sun.
And if to cool air at once and strongly? As there is it at night frosts in the spring or in the fall. The situation will be similar described above. Only beautiful snow-white needles will become ornament for vegetation. Water from a vaporous state will pass into firm. Hoarfrost will drop out.
On a windowpane everything occurs likewise. In the house warmly, and on the street a frost. Moisture from warm house air is condensed on a cold surface of a window and freezes, turning into small crystals. Glass becomes covered with ice.
Draws patterns a frost on a windowpane...
If glass at your window absolutely equal and clean, then the drawing on glass does not come out. Nothing will be able to forbid processes of condensation and freezing. But here patterns will not turn out. Before your eyes the wonderful white field will appear. However glass has not an ideal surface. It is covered with small roughnesses and scratches. Constantly settle parts of house dust and dirt from the street on glass. On these roughnesses and scratches first of all ice crystals are also formed. Then to them still crystals, and are attached to those crystals others... And the entertaining pattern appears. Keen edges of scratches can become the reason for the patterns having intricate the name - "trikhita". The structure of such picture has fibrous character. At first on a crack "stalk" is formed. From it, departing from microscopic chips at edges of a scratch, graceful, fancifully curved "fibers" will begin to run up in different directions. When the humidity in the apartment raised, and temperature outside the window goes down not really sharply, at first glass becomes covered by a thin film of water. Then, freezing, at a window the pattern reminding the fairy forest will take shape. The name at such drawings is not less entertaining – "dendrites". Gravity tightens the smallest droplets of water to the lower edge of a windowpane. Therefore moisture accumulates more here. Therefore "branches" are thicker at the very bottom. And than above, that patterns become thinner, more and more graceful also azhurny.