Thunderstorm activities in w. bengal 1968¿70

The information concerning lightning activities in an area has an important bearing on the assessment of the vulnerability of transmission lines in that area to lightning flashes. The question arises as to the level of protection that should be aimed at for a given standard of service. The probability of a flashover for a given level of protection can be obtained from the probability of thunderstorm severity Lightning-flash counters of the design approved by the CIGRE study group 33 for worldwide adoption were built, for automatically recording the lightningstroke incidents, in collaboration with the electricity-supply authorities of Bengal. The primary purpose of the survey is to provide information on the varying degree of thunderstorm activities in different seasons. Data derived from the survey are being used also for examining the accuracy and range of an automatic lightning-flash counter. The agreement between the lightning day as defined by a lightning counter and the day with perceptible thunder can be established if the observer can hear the weak thunder. The lightning counter is on the average more reliable than the audible sounds, since the human factor plays a more important part than the uncertainty of the instrument. The present report covers the work carried out during 1968¿69 with the aid of a grant provided by the Council of Scientific & Industrial Research. The authors are very grateful to the Director Ceneral of the CSIR for the assistance given and also to Jadavpur University for providing the facilities for continuing the investigation.