Climatology of lightning over Indian region and its relationship with convective available potential energy

摘要

The spatial distribution of convective available potential energy (CAPE) and lightning activity in different seasons over the Indian region have been studied to find out the dependence of lightning activity on CAPE. It is observed that the lightning activity over the Indian region is not controlled by CAPE alone during pre-monsoon season. The prevailing meteorological conditions and orography over northern India, central India, northeast Pakistan and Bangladesh provide favourable conditions for formation of thunderstorms, and hence, lightning activity is higher in spite of lower value of CAPE over these regions compared to other parts of Indian region. During the monsoon season, lightning activity and CAPE are found to be better correlated with each other compared to other seasons over central and north India. It has been found that the high mountains of Himalayas generate strong updrafts necessary for the deep convective events by interacting with prevailing winds and the diabatic heating and radiative cooling of mountaintops create conditions favourable for convections. The diurnal variation of lightning activity at stations over the foothills of Himalayas showing a strong peak in lighting activity after midnight supports the idea that radiative cooling at mountaintops can create a moisture convergence at foothills and trigger the convections.