Why is it snowing when you are afraid?

Surprised, it snowed, which is normal; Related to climate;

Snow is solid water, which falls from the mixed clouds to the ground in the form of snowflakes. Precipitation consisting of a large number of white opaque ice crystals (snow crystals) and their polymers (snow masses). Snow is a natural phenomenon that water falls after condensation in the air, or refers to falling snow; Snow is the solid form of water. Snowfall only occurs under the influence of very cold temperatures and extratropical cyclones, so the probability of snowfall in subtropical and tropical areas is relatively small.

shape

Snowflakes are mostly hexagonal. Because ice molecules are mostly hexagonal, there are many patterns. Hexagonal flake ice crystals have different saturated vapor pressures because of their different curvatures on the surface, edges and corners, in which the saturated vapor pressure is the largest at the corner and the smallest at the plane.

Under the same actual water vapor pressure, the sublimation growth of ice crystals is different because of the different saturated water vapor pressures of each part. For example, when the actual vapor pressure is only greater than the plane saturated vapor pressure, the vapor only condenses on the surface, forming columnar snowflakes.