The article explains why icicles appear, how to make them yourself and what is their danger in a big city.
Cold
There are many climatic zones on our planet. There are both hot regions and those where summer never happens, and human life is almost impossible. In some places it almost always rains, while in others it is very rare, and it is difficult for their inhabitants to imagine frequent thunderstorms, and even more so water in its non-liquid state - snow and hail.
But all the cold areas and places where the temperature drops below zero during winter periods have one more common phenomenon in common. These are icicles. So why do icicles appear? First you need to understand what cold and ice are.
Definition
According to conventional terminology, cooling is a phenomenon that occurs due to a decrease in temperature or the removal of heat from an object in one way or another. For most living forms, low temperatures are destructive, as are high ones. And by the way, absolute cold is denoted as -273.15 degrees Celsius. Under such conditions, not only water freezes, but metals become brittle, like glass, and practicallystops the movement of elementary particles in matter.
Ice
When the temperature drops below zero degrees Celsius, water turns into ice. This is the solid state of matter, which usually has a liquid form. But if there is no rain in winter, and all the liquid freezes, then why do icicles appear on the cornices of houses? The thing is that during the winter periods the temperature can vary in a fairly wide range, and the precipitation will begin to melt, and then the new frosts will stop it. That is why the water, which was snow, begins to drain from the roofs of houses, and as the temperature drops, it gradually freezes, due to which the drops, sliding along the bases of icicles, do not reach the ground in full, leaving part of the liquid in the form of ice.
But sometimes in winter there is no positive temperature at all, but frost can still be observed. Why do icicles appear in this case?
Warmth
In this case, the heating of houses comes into play. According to statistics, in winter, most houses lose up to 30% of heat through the roof, and the snow, albeit slowly, but still melts. This is especially true in private homes.
Danger
These ice formations are quite dangerous. Especially in cities where there are many high-rise buildings. And all because getting to their cornices is very problematic, and icicles sometimes grow to enormous sizes. As a result, when falling, they can kill a bystander. And, frankly, get hit on the head with even a small piece of ice that fellfrom the 15th floor, so-so fun.
That's why every winter the utilities put a lot of effort into knocking down icicles.
How to make an icicle?
There are several ways. The first, the most "natural". On a frosty day, you need to stock up on patience and a bottle of water. Then find an object on the street from which the liquid would drain slowly and evenly, and ideally - drop by drop. This process is not fast, but with the appearance of the first ice, things will go more fun.
The second way to make it is possible at any time of the year. You just need to prepare the appropriate form, pour water and place in the freezer of the refrigerator. But the main thing to remember here is that the liquid expands greatly when it freezes and can destroy the mold material, so glass is not suitable for it.
Well, the third is to get a block of dry ice and cut a narrow long cone in the form of an icicle out of it. True, it will not be an icicle in the usual sense, since dry ice consists of frozen carbon dioxide, which does not melt, but evaporates. It can also cause cold "burns" to the skin.
Now we know how icicles appear and how to make them.
