What is the temporal and spatial distribution of the rain?
This special weather, the rime, mainly appears in mountainous areas and lake areas. In most areas of China, the snow cover appears from December to March of the following year. The distribution characteristics of the annual average number of rainy days in China are that there are more in the south and less in the north (there is very little low temperature near zero in South China because of warm winter, so there is neither hail nor rainy days); There are many wet areas but few dry areas (especially the mountainous areas have the most rainy days). Almost all stations in China have an annual average rainy day of more than 2 ~ 3 days, but most stations in the plain area have an annual average rainy day of less than 5 days.
In general, the occurrence time of rime is more than one month from the first ten days of January to the first and middle days of February, with the characteristics of early in the north, late in the south, early in the mountains and late in the plains, while the end date is just the opposite. In mountainous areas with higher terrain, the onset of the rime is early, the end is late, and the rime period is prolonged. For example, in Guangmingding of Huangshan Mountain in southern Anhui, the rainy season usually begins in early November and ends in early April of the following year, lasting for five months. According to relevant figures, the rainy weather in Jianghuai area usually occurs once every 2 ~ 3 years in Huaibei area and once every 7 ~ 8 years in Huainan area. If you are in a mountainous area, there will be a big difference between the valley and the top of the mountain. In some low-lying areas of the mountainous area, there is little rain, while in the high-rise areas of the mountain, there is rain almost every year.
in the 196s, there was no rainy season in Guangzhou, and only .1, .7 and .5 days in Shanghai, Beijing and Harbin respectively. The weather station with the largest number of rainy days in China is Emei Mountain Meteorological Station, with an average of 141.3 days (167 days in the maximum year), followed by Jinfo Mountain with 7.2 days (93 days in the maximum year), and Lvcongpo in Badong, Hubei Province with 61.5 days (9 days in the maximum year), which usually occurs in southern mountainous areas. There are few and not serious rainfalls in the north, and even less in arid areas. Huajialing, Huashan and Tianchi in Changbai Mountain, which are commonly known in Gansu Province, have frequent rainy days in the north. Their average annual rainy days are 29.6, 19.8 and 18.5 days, and most of them are also high mountain stations.
In the winter, there are more frequent rainy seasons in the northern regions with cold winters and warmer spring and autumn seasons. For example, the rainy season at Tianchi weather station in Changbai Mountain is concentrated in May, with an average of 5.7 days, followed by September, with an average of 3.5 days, and there is no rainy season from December to March in winter due to the low temperature. In the south, colder winters prevail. For example, the Emei Mountain weather station has an average of 26.4 rainy days in December and 24.6 in January. Even in December, January and March of some individual years, there have been rainy days every day.
the harm caused by the rain-break has a great relationship with its duration. There was a rainy season in Shanghai on January 15-16, 1957, which lasted for 3 hours and 9 minutes. The longest continuous rainy season in Beijing is 3 hours and 42 minutes, which occurred on March 1-2, 1957. The longest duration in Harbin was 28 hours and 29 minutes, which took place on October 18-19, 1956. The longest continuous rainy season in China also occurred in Emei Mountain, which lasted from November 15th, 1969 to March 28th, 197, that is, it lasted for 3198 hours and 54 minutes. Followed by Hengshan Nanyue for 137 hours and 57 minutes (from December 24, 1976 to February 19, 1977), and the third place was in Xuefeng Mountain, Hunan Province for 1192 hours and 9 minutes (from December 25, 1976 to February 12, 1977).
The diameter of rime ice is usually 4 ~ 7 mm, and there are also several hundred mm. The largest diameter of rime ice in China appears in Nanyue, Hengshan Mountain, reaching 12 mm, followed by 711 mm in Lvcong Slope in Badong and 648 mm in Xuefeng Mountain in Hunan Province.
The method used by weather stations to observe the diameter of the accumulated ice in the rime is as follows: As the rime is freezing, the conductor becomes thicker and thicker, but when the rime accumulates to a certain diameter, the "rime popsicle" is bound to break gradually. At this time, meteorological observers simply remove the residual ice and let the rime freeze on the conductor again. If it is located in a high mountain, it may continue to be cleared several times or even more than a dozen times, and the process of rain is over. According to the regulations of the meteorological department, the sum of the maximum diameters during each fragmentation is the maximum ice accumulation diameter during all the glaze processes.
On November 24th, 1962, an ice accretion occurred in Hengshan, Hunan Province, with a weight of 16,872g, or 16.872kg, on each meter of conductor, which is the champion in all records in China. Other heavy records include: 15,616 grams of Xuefeng Mountain in Hunan, 12,148 grams of Huangshan Mountain, 5,468 grams of Lushan Mountain and 5,44 grams of Jinfo Mountain. The last snow storm occurred in Shangqiu County, Henan Province from March 5 to 9, 1966. The maximum diameter reached 16 cm, and the maximum ice accumulation diameter reached 14 g/m, which was also an extremely rare record in the plain weather station in the 196s.