This year's lunar calendar october eighteen is a small snow, the small snow festival is the second winter festival, for the middle of the month, at this time the handle refers to the sea, the heavens and the earth are cloudy, the temperature is rain, the cold is snow, the cold is not deep snow, so it is called small snow. As the old saying goes, "A little snow and a little snow, no end and no rest", why is there such a saying?
When the sun runs on the ecliptic to 240 degrees, it is the time of the small snow festival, the ancients divided a solar term into three weathers, every five days for one weather, the three weathers of small snow are: one weather is hidden; the second weather rises and the earth's atmosphere falls; and the third weather is blocked into winter. This means that when the snow season comes, the rainfall is greatly reduced, the air is dry, and it is difficult to see the rainbow again.
At this time, the yang in the air rises, and the yin in the earth sinks, resulting in the impassability of heaven and earth, the non-intercourse of yin and yang, the loss of vitality of all things, and the blockage of heaven and earth, thus entering the cold winter. Originally, the turbid qi in the sky should sink, the yang qi on the ground should rise, and in the process of rising and sinking, the two kinds of air flow will have "yin and yang sympathy", and all things will be born.
However, when the snow is throttled, because the sun is far away from the northern hemisphere, the yang on the ground cannot be heated and rise, and the turbid qi in the sky cannot sink, so the yang in the air rises, the yin in the earth sinks, the higher the sky, the farther the earth, the more incompatible with each other, everything is not born, so it is called occlusion into winter, that is, it is not accessible up and down, so the grass and trees wither, and everything withers.
However, the light snow festival is only the beginning of the cold winter, at this time the weather is not particularly cold, so in this festival there may be snow, it may also rain, because the temperature is not particularly low, the temperature is rain, the cold is snow, so it is called light snow. Therefore, the light snow festival is the easiest to form "sleet".
Sleet is a relatively special precipitation phenomenon, which means that there are still snowflakes in the rain, but this snowflake is because the temperature is high, and after melting, it becomes Xiaoice crystal. But the phenomenon of "sleeting" is generally short-lived, either quickly turning to snow or turning into rain.
The formation of sleet is more demanding on the temperature, first of all, the temperature at high altitude should be lower than zero degrees, so as to form snowflakes. In the process of falling snowflakes, encountered the warm air layer below, and the thickness of the warm air layer is about three hundred meters, when the snowflakes pass through the warm air layer, part of the snowflakes melt into rain, and some snowflakes do not melt, so that sleet is formed.
If the temperature of the warm air layer is higher, or the thickness is larger, the snowflakes will all melt, and it will be rain that falls. If the warm air layer is cooler or thinner, the snowflakes will not melt. However, during the melting of snowflakes, the temperature of warm air will continue to decrease, so sleet generally does not last too long.
The climate of the light snow festival is not too cold, and it is most likely to form sleet at this time. If there is sleet in the snow festival, it means that the temperature of the ground is still relatively high, otherwise it is snowflakes that fall. Therefore, sleet means that the temperature above the ground is still relatively high, and there is a thicker layer of warm air.
Because the snow festival is already fifteen days after the beginning of winter, if sleet is formed, it means that the previous weather is still relatively hot and the sun is still stronger. Only when the temperature is higher, the air with moisture on the ground will be heated and rise.
It should be known that the warm air layer of about three hundred meters can not be formed in a day for winter, which means that there are more humid and hot air that has risen to the high altitude, and these hot and humid air will form Cumulonimbus clouds in the high sky, either becoming snowflakes falling or becoming rain falling.
Therefore, "small snow and sleet, no end and no rest", which means that if there is sleet during the small snow festival, there will be more rain or snowfall after that, and endless is just an adjective. Because the hot and humid air that had previously risen into the sky would continue to turn into rain or snowflakes falling.