Lightning Features Of Thundercloud In Northwest China

When gorgeous lightning slips cloudy sky, humankind pays more attention on thunderstorms, which were regard as God in ancient. With advantage of technology, many devices conduce to approach, understand and unclose lightning nature. The considerable complicated landform including desert, Gobi, glacier and so on result in different thunderstorm distributing and lightning frequent in Northwest China. Based on 33 years weather stations data, Doppler radar data and lightning data that come from Gansu lightning detection networks, spatial and temporal thundercloud distributing and lightning in strong convective were calculated, the result reveal that thundercloud distribution have three geographic cents and lightning present distinctively features. Furthermore, the non-inductive charging conditions were discussed by one-dimension thundercloud model. The main conclusion is as follows:1. The most frequent thunderstorm happened on summer, second on spring and on autumn, and nearly none on winter. Geographic distribution of thundercloud days takes on three cents, and there discrete degrees in center were bigger than these of other areas. The thunderclouds in Tibet plateau are prone to producing hails.2. There many lightning occur on spring, autumn and fall, which compose of 84. 3% negative ground flashes and 15. 7% positive ground flashes, and their daily change have two-peak value.3. The frequency of lightning popularly show maximum before hails and lightning hourly distribution can sign out the trace of hail cloud. Both of them help identification of hail.4. According to the analysis in a case of convective weather, Liquid water content (LWC) is an important factor for identifying hail, and cloud flashes which are majority linearly locate at the route of hails, but ground flashes whose majority polarity are negative focus on hail areas.5. Topographty play a significant role on intense convective weather development and there are certain connection among center of flash intensity, hail location and even rainstorm areas. The electric current of flash can reveal some characteristic of electric fields in thundercloud. Forepart radar echo come into being on upper level and respectively extend upwards and downwards, and 4km altitude is the strongest echo region. Meanwhile, dense lightning distribute over the region which radar echo exceed lOdBz, and lightning prior to radar echo center.