The Book presents works on characterization of different processes inside thunderstorms using VLF sferics and Vertical Electric Field monitor (VEC). From the measurements of electric field variation during thunderstorm it is observed that the tri-pole charge structure and the Lower Positive Charge Centers (LPCC) seem to be much dynamic over North-East India. Several enhancement and decrement in the sferics level occurred due to the vigorous charge separation during the precipitation and during the lightning processes during the AILA cyclone activity. One major part of the current work is devoted to the climatology and electrical characteristics of thunderstorms of North East India located in the foothill of the Himalayas. This type of work is the first of its kind in this region and it will provide valuable scientific information regarding thundercloud activities in North East India.