INTRACLOUD LIGHTNING DISCHARGES IN THE LOWER PART OF THUNDERCLOUD^*

From analysis of observational data of thunderstorms in Gansu,China,it was deduced that the electric structure of thunderclouds in this region is often positive charge in the upper,main negative in the middle layer and another positive charge,large in magnitude and extensive in dimension,in the lower part.Intracloud discharges often take place between the main negative charge and lower positive charge instead of upper.Case analysis of 6 intracloud discharges in two storms on August 3 and 4,1986 shows that the centers of these discharges and the dipole moments destroyed were at the altitude of 3.8-6 km msl(7.6-13.5℃) and 18-40 C km,respectively.