Spatial Distribution Characteristics of Precipitation in Hunan Province

? Hunan is abundant in rainfall, with an annual average rainfall of 1200 ~ 1700 mm, but its temporal and spatial distribution is very uneven.

Hunan is located in the south of the Yangtze River, with low latitude, subtropical monsoon humid climate and obvious continental characteristics.

Winter is often controlled by dry and cold air masses from Siberia and Mongolia Plateau, which is relatively dry and cold. Under the influence of quasi-static front and cyclone activity, it can bring some rain, snow and frost weather.

Summer is mostly occupied by warm and humid air masses at low latitudes, and the climate is hot and rainy.

In spring, there is a confrontation between the north and south air currents on the ground, frequent cyclones and frontal activities, more rain and changeable weather.

Autumn is a transitional season from summer to winter. The subtropical high forces gradually withdrew to the south, and the northerly airflow gradually controlled the whole territory. The whole province presents autumn weather with very stable vertical structure of exit layer and low humidity.

The influence of Hunan climate on agricultural production;

The main disaster affecting the development of agricultural production in Hunan is drought, followed by flood, followed by low temperature chilling injury and high temperature chilling injury. Although there is little precipitation in rainy season this year, and there is a serious shortage in some places, the drought is not very serious so far because of the uniform distribution of precipitation periods. Only a few towns have floods, and there is no cold damage in spring.

The hot weather lasts from mid-July to early August, lasting for 17~ 19 days, with the longest history of more than 40 days, with the highest temperature of 39.5℃ and the highest temperature in history reaching 4 1℃.

On the whole, Hunan has been a good year. Hunan recovered quickly this spring. From mid-March to late April last year, it was a frequent period of low temperature and rainy weather or "cold in late spring", which happened to be the spring sowing and seedling raising period. If low temperature occurs during this period, seeds and seedlings will rot. If no measures are taken, it will delay the season and reduce the output of the year.

The temperature is high in May, and there is no "low temperature in May". Fortunately, the low temperature didn't happen all spring. Spring sowing crops have a bumper harvest per unit area.