Is there a cold spring in the middle and late March?

There will be a cold spring in the middle and late March every year.

According to the Meteorological Index of Late Spring Cold (GB/T 34816-20 17) formulated in 2017, the meteorological late spring cold refers to the phenomenon that it is warm in the early spring, cold in the late spring and the temperature in the late spring is obviously lower than normal.

The cold in late spring is mainly caused by long-term rainy weather or frequent invasion of cold air, or by strong radiation cooling on sunny nights under the control of cold anticyclone.

If the average temperature in late spring is more than 2℃ lower than normal, it is considered as cold weather in late spring, which can cause harm to agricultural production, especially in the early stage of late spring, which is higher than normal, and in the later stage, the temperature is lower.

Simply put, in spring, the weather gets warmer, and the temperature drops obviously due to the invasion of cold air, which is harmful to crops. This kind of "warm before spring, cold after spring" weather is called late spring cold.

standard

The late spring cold mainly refers to the weather phenomenon that the average temperature drops below the same period of normal years and lasts for a period of time under the background of the general increase of temperature in spring (March-May) in China, affected by the frequent cold air going south in the north or the continuous rainfall in the south.

As for the extent and duration of cooling, local standards are slightly different. For the northern region, the cold spring means that the cold air force is enhanced and the temperature drops sharply; For the southern region, it is usually associated with low temperature and rainy weather.

Agrometeorological experiments show that the average daily temperature is less than12℃ and the maintenance period is more than 3 days, which is not conducive to seedling growth. If the cooling is accompanied by rainy weather, the harm will be even greater, which is a relatively recognized indicator. In southern China, the spring sowing time comes first and then comes, and the period and intensity index of the cold spring are also slightly different.

For example, Guangdong refers to the following low temperatures in the middle and late March in central and southern Guangdong as late spring cold:

1, daily average temperature ≤10 ~12℃ for 3 ~ 4 days or more.

2. The average daily temperature is ≤ 15℃, and the sunshine is ≤2 hours for 7 consecutive days or more. ?

China has a vast territory, different weather and climate conditions and different victims, so the standards of meteorological disasters will be different.