It is crisp in autumn in Hebei, and the temperature difference between day and night is large. There is frost in these areas.

Hebei expects frost in northern Zhangjiakou, northern Chengde and northwestern Baoding, and frost in Bashang area.

Meteorological Observatory issued blue warning information of cold wave. Compared with other areas, it may be common for residents in this area to enter the cold weather prematurely, but many residents are caught off guard by the sudden drop of temperature like this one. Before August, the temperature had plummeted to zero degrees Celsius. This extreme weather not only has a serious impact on residents' lives, but also causes huge economic losses to local residents who mainly grow crops.

Frost is a common agrometeorological disaster, which means that the temperature drops suddenly and the surface temperature drops below 0℃, causing damage to crops and even death. Frost usually appears in autumn, winter and spring.

Harm to crops

Autumn harvest crops such as corn, soybean and cotton are very sensitive to frost before maturity. Take corn as an example, if it suffers from early frost during grain filling, it will not only affect the quality, but also reduce the yield. When the temperature drops to 0℃, the corn is slightly frosty, and the leaves are the first to suffer. The nutrients for corn filling are mainly produced by photosynthesis. After freezing, the leaves turn yellow, which affects the photosynthesis of plants and reduces the nutrients produced.

Due to the decrease of nutrients, corn filling is slow and grain weight is reduced. If the temperature drops to MINUS 3℃, there will be severe frost, and besides a lot of fallen leaves, the ear neck will freeze to death. This not only seriously affects the photosynthesis of maize plants, but also cuts off the channel of transporting nutrients from stems to grains, and the filling is forced to stop, which often leads to a sharp decline in yield. When the first frost appears, if the crops are ripe and harvested, no matter how serious it is, it will not cause losses.

The above contents refer to Baidu Encyclopedia-first frost.