On cold days, the wind is small, the moon and stars are clear; in the early morning, opening the window and looking out, we see a thin layer of white snow on the roof of the house under the grass. If you flip a tile to see it, you can see that its underside also has white frost-like snow.
Every year in the summer of October, we often see the record “Suddenly.” We’ve seen snowfall, we’ve seen rain, but who has seen the mist? Does hoarfrost come from the sky? During the daytime, the ground is shone by sunlight. The air temperature is relatively high; water on the ground often evaporates, making the air layer near the ground always contain a certain amount of water.
In late autumn, winter, and early spring, cold air at night, especially cloudless nights, cold air accumulates near the ground. When cold below 0 ° C comes into contact with cold objects, water vapor in that part will stick to the object and form ice crystals. That is frost. Because hoarfrost is the steam that condenses on the ground, not falling from the sky, wherever it is, as long as there is a condensation condition, it will form, sometimes under a piece of tile or a stone slab can also see frost.
The exposed objects and formation conditions in the cold season are different. Because of the small heat ratio, after the diffused heat becomes cold, it is easy for the salt fog to appear; the wood can diffuse heat from the top and bottom. Moreover, it can be hung on the water surface, so the wood is slightly absorbed. Water is abundant, so it is easy to mist, bricks with many crevices and voids have good thermal insulation properties; once it is cold, the heat of other objects is difficult to transfer to it, so it forms frost very slowly.
On the ground, the leaves of grass and leaves can both diffuse heat. Moreover, the thin leaves are easily cooled, so the frost occurs. Plow soil is spongy because it is not easy to absorb heat from the ground, so its surface is easier to form salt fog than clumped soil. Because their frost forming conditions are different, their frost appearance is also different.