How is the rime formed? What conditions do you need to form a rime?

The formation of rime mainly needs two conditions:

1, the temperature is low enough, at least below zero;

There is enough water vapor in the air, but it is impossible to rain or snow.

When the temperature continues to be low, the water vapor in the air meets branches or other low-temperature objects with low enough temperature, condenses on the objects, and gradually accumulates to form rime.

The harsh conditions for the formation of rime are, first of all, the cold and long winter, and enough water vapor in the air. Secondly, the formation of rime requires both sunny days and partial cloudy days, as well as calm, or the wind speed is very small. Clouds in the sky are like quilts of the earth. When there are clouds at night, the outward long-wave radiation is weakened, which makes the ground temperature drop slowly and the temperature difference between day and night is relatively small, so that the water vapor in the air near the ground will not condense. If this quilt is lifted, it will emit more heat, lower the ground temperature and provide the necessary conditions for water vapor condensation. Strong wind is the natural enemy in the process of rime formation, which can always blow away the ice crystals with loose structure in the process of rime formation. Even if the rime gathers together, it will be blown away without a trace, and the conditions of small wind or still wind provide a guarantee for the condensation of water vapor into rime. Generally speaking, in winter, sunny days are unlikely to appear at the same time as still winds or breezes. In addition, when there is supercooled fog, it is especially beneficial to the growth of ice crystals on ground objects. At this time, white ice flowers are formed on wires and branches, which is called "rime". When there is fog and the temperature is higher than 0℃, fog drops stick to leaves or other objects, which is called "fog condensation" and is most common in forests.