Official website, the administrative office of Ali region, inquired that on May 6, 2009, the ultraviolet index of Lhasa was 32; On May 7th, the ultraviolet index in Lhasa was 42. May 8, Lhasa ultraviolet index 34; On May 9, the ultraviolet index of Lhasa was 35; On May 10, the magnitude of the ultraviolet index in Lhasa was 36, and the index grades were all five, and the index intensity was "very strong". According to "Journal of Earth Environment", the highest spectral intensity of the sun in Ali and Lhasa both exceeded the highest spectral intensity of AM0, indicating that the ultraviolet level in these two areas is very high, both of which are level 5.