When and how did the frost form? What's the difference between first frost and Chushuang?

As we all know, weather changes seriously affect people's lives. First frost is a weather phenomenon, so when is first frost? How is the frost formed? Next, come with me to see the characteristics of frost weather!

When is the frost? The general cycle of early and late frost in China is as follows: the first frost appears in the northeast and Inner Mongolia 10 from early September to early June, and the late frost appears in the middle and late April; The first frost in North China occurs from the first ten days of 10 to the first ten days and the middle ten days of10/0, and the late frost occurs from the middle of March to the first ten days and the middle ten days of April. The fundamental way to prevent frost is to prevent it beforehand. The main methods are: breeding cold-resistant and early-maturing varieties, sowing early in a short period of time to avoid the harm of low temperature frost; Strengthen field management and improve the cold resistance of crops.

Frost means that during the warm period of a year, the temperature of soil surface and plant surface drops enough to cause crop injury or death. Therefore, when frost occurs, the temperature of the near-surface layer can generally be below 0 degrees; It can also be in the range of more than 0 degrees and less than 5 degrees. When there is frost, white ice crystals may not appear. This situation is called dark frost in some places. Box freezing can be divided into spring frost and autumn frost. Spring frost appears in late spring, when many crops have resumed growth. During this period, crops are weak in cold resistance and vulnerable to low temperature damage, which affects their growth. When autumn frost, especially early autumn frost, appears, the weather is still relatively warm, and crops have entered the wintering period before they stop growing. Therefore, the appearance of frost will stop the growth of autumn crops prematurely, leading to the decline of yield and the deterioration of harvest.

Definition of how frost is formed: when a weather station observes that there is white frost on the ground, the lowest temperature on the ground is ≤0℃ or the ground is frozen, it is said that there is frost or ice on the ground.

Advection frost (1) is cooled to 0℃ or below due to the invasion of strong cold air, which leads to the formation of frost. This frost has a wide attack range and a large cooling range.

(2) Radiation Frost When there is no wind or breeze at night, radiation cooling will reduce the temperature of ground or near-earth objects to 0℃ or below, resulting in frost. This frost occurs in a relatively small area.

(3) Frost caused by advection radiation, cold advection and radiation cooling. This frost has a serious impact. In addition, some areas also produce a depression (valley) frost. At night, the air near the surface layer cools down, and the cold air on the slope slides down, accumulating in depressions or valleys to form frost, which appears more than in autumn. This is consistent with the agricultural proverb "Frost hits the depression" in Qinghai.

On the surface, it seems that the first frost is getting colder and frostier. To be exact, frost does not fall from the sky, but is white loose ice crystals formed by condensation of water vapor in the air near the ground or on the ground. With the arrival of the first frost, crops that are not hardy have been harvested or will soon stop growing, and the vegetation has begun to turn yellow, showing a scene of late autumn.

Frost means that in the growing season, the temperature on the soil surface or near the plant canopy drops below 0℃ in a short time at night, the temperature on the plant surface drops rapidly, the water in the plant freezes, the metabolic process is destroyed, and cells are squeezed by ice cubes, causing damage.