What does Frostfall mean: It means that the weather is getting colder and frost is starting to fall.

Significance of Frostfall

Every year, in the middle and end of October, it's time for Frostfall, the last of the twenty-four traditional festivals, and the last of the fall, which marks the transition between fall and winter. At this time, the temperature difference between morning and evening is very big, sometimes the temperature at night has reached 0 degrees below, the ground or plants directly condensed into ice needles can be seen, thus proving that the frost in the twenty-four solar terms, heralding the weather gradually become cold.

After the frost, the plants are not alive at all, which shows that the frost is merciless and cruel. Of course, most of the frost can only be manifested in the north, while in the southern region, there is no frost that can come down even when it reaches the season of frost.

While it is said that after the frost, the wind cooling increase, the temperature gradually become cooler, but frost and frost is still a difference, the crops encounter frost that the harm will be big, and encounter frost crops will be much less harmful. Because of the water vapor condensation of the frost covering the foliage of the crops, not only can not harm the crops, when the water vapor melting may also release a lot of heat energy to.

Frost and crops

Frosting. The "seventy-two wait for the lunar calendar": "In the middle of September, the gas is purified and condensed, and the dew is crystallized into frost. At this time, China's Yellow River basin has appeared white frost, thousands of miles of fertile land, a silver ice crystals glittering, at this time the leaves withered and yellow, in the leaf drop. Ancient book "twenty-four seasons to solve" said: "gas and frost fall, yin began to condense also."

It can be seen that "frost" indicates that the weather is gradually becoming colder, and frost begins to fall. Meteorologically, the first frost in the fall is called "early frost" or "first frost", and the last frost in the spring is called "late frost" or "final frost". The last frost in spring is called "late frost" or "final frost". The period between the last and first frosts is the frost-free period.

Frost is water gas condensation, water gas how to condense into frost? The Southern Song poet Lu Benzhong wrote in "Nan Ge Zi - Travel Thoughts", "The post invades the slanting moon, and the stream bridge is full of late frost." Lu You wrote in "Frosty Moon", "The withered grass is white with frost, and the moon's shadow is new in the cold window." It shows that frost appears on a clear moonlit night in autumn.

There are no clouds in the autumn night, the ground as uncovered by the quilt, a lot of heat dissipation, the temperature plummeted to below 0 ℃, not much water vapor by the ground will condense in the creeks, bridges, leaves and soil, the formation of fine ice needles, and some of them become hexagonal frost flowers. Frost can only be formed on a sunny day, and this is why people say, "Frost is strong in the sun".

Frost climate characteristics

Because the frost is frost (sometimes no frost called black frost), so the fall frost and spring frost collectively referred to as frost. Frost festival contains the meaning that the weather is getting colder and frost begins to fall. In the southern region of the latitude south, the average temperature is mostly around 16 ℃, and there are three more seasons from the date of the first frost. In the river valley area of southern China, it will not see frost until mid-winter.

Of course, even in the same latitude, due to the altitude and topography of the different, advective layer of air temperature and humidity there are differences in the period of the first frost and the number of frost days will not be the same. At the time of frost, the cool autumn wind has blown to the flower city of Guangzhou. The average temperature in the northern northeast, eastern Inner Mongolia and most of the northwest has been below 0 ℃.