Temporal and Spatial Distribution Characteristics of Hail Disasters in the Past 110 Years in Chongqing

On the base of related hail data in Chongqing from 1901 to 2010, this paper analyses and researches in detail the hail’s spatial-temporal distribution characteristic. The results indicate that the hail disasters of Chongqing have an uneven distribution characteristic on spatial and temporal. The hail occurrence has obvious yearly, monthly and daily variation. There were less hail disasters in early 40 years of last century. After that it increased significantly in each age till 1970’s. The hail’s number is highest in 1975. But in recent 30 years, the yearly hail number of Chongqing has decreased. Except January, there has possibility of hail disaster in Chongqing. But the hail disaster mainly concentrated from March to August. And April has highest hail number. The hail disaster occurs mainly from 14 to 2 o’clock in the next morning. At spatial distribution, the eastern part of Chongqing had more hails than the western part. The northeastern part had more chances of hail disaster than southeastern. The reasons of this spatial distribution are landform and cold air moving path.