Thunderstorm Electrical Parameters vis-a-vis Rainfall and Surface Air Temperatures over a Tropical Inland Station, Pune, India

The relationship of lightning with rainfall and temperature is investigated on the basis of a four-year (2004-2007) data set over the Pune region. It is found that the annual variations of stroke count and rainfall both are bimodal with the first peak value of rainfall showing a one month time lag from the first peak value of stroke count. This is attributed to the prime period of the onset phase of summer monsoon rainfall over the Pune region. Lightning is found to be highly correlated with rainfall (r = 0:792, significant at 0.4), but by excluding the data for the month of July. The annual variation in the monthly mean surface wet bulb temperature and stroke count for the period under study over the Pune region shows similar peaks in June and September. These two parameters are well-correlated and show a positive correlation coefficient of 0.59, which is significant at the 5 level. A massive reduction in the lightning stroke count during July and August is attributed to low ground temperature that gives rise to lower updraft velocities and shallower cloud depth. There is good parallelism in the variation of surface air temperature and Point Discharge Current (PDC). The correlation coefficient between these two parameters is 0.934, and it is highly significant