午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

For a further study on the temporal characteristics of lightning current wavefront time and the demands of lightning protection engineering design, lightning risks management, and the lightning disaster prevention， the lightning current data observed by LLS (Lightning Location System) from 2007 to 2013 are used to analyze the annual, seasonal, monthly, and daily variation of lightning current wavefront time, its cumulative probability, and cumulative probability density by the mathematical statistics method. The results show that the mean wavefront time of positive lightning is 48 μs; the wavefront time of negative lightning and the total number of lightning is 36 μs; in the whole year, the shortest wavefront time for positive lightning is in July, and its monthly variation presents a Vshaped variation. On the other hand, the wavefront time for negative lightning and the total one is shorter between May and July than in any other months, and its variation appears to be an Ushaped style. The wavefront time of positive lightning changes obviously in different seasons and days, but those of negative lightning and the total one stay stable. When the wavefront time is less than or equal to 10 μs, the cumulative probabilities of wavefront time are 955%, 997%, and 996% for positive lightning, negative lightning, and the total one, respectively. The wavefront time of longer than 15 μs occupies 95% of the total lightning, and 50% for that of longer than 31 μs, only 5% for that of longer than 60 μs. When the wavefront time is 2 to 3 μs, the cumulative probability density of wavefront time is the greatest for these three kinds of lightning. The months with low temperatures have longer wavefront time, and on the contrary, the wavefront time will be shorter. The reason seems to be connected with the amplitude of lightning current, whose specific reasons need to be further investigated.