A simple model for determining the potential risks of lightning strokes over the cities of Nairobi and Mombasa

Abstract

This study examines the cloud to ground lightning discharges over the cities of Nairobi and Mombasa including their environs. Ground based and Satellite-derived meteorological data were utilized in this study and included thunder events, total rainfall, number of rainy days, maximum rainfall in 24 hours, relative humidity, minimum and maximum temperature, wind speed and direction and Cold Cloud Duration (CCD). In the context of disaster management, the synergistic approach to risk management involves four closely related phases, one of which is the scientific analysis of specific hazard. This is the phase addressed in this study. A risk indicator based on physical and statistical characteristics of thunderstorms at the two locations was developed by examining the patterns of deviations from the mean thunderstorm events and their frequencies. Various aspects of the lightning risks at the two areas are described and discussed. Model results indicate that higher risks of lightning stroke occurred during the long rains season (March to May) as compared to the short rains (September to November) season. This was attributed to higher frequency of thunderclouds during the long rains season. The rain generating mechanisms during the long rains were observed to have higher frequencies of thunder events. The dry season (December to February and June to August) exhibits lowest lightning stroke risks. It is hoped that the results from this study may be of use to the various sectors of economy that need to take into account the dangers/risks of lightning strokes into their day to day operations so as to minimise or avert disasters from lightning strokes. Some of the sectors that may benefit from the results of this study include the Kenya Oil Refinery Depots, Kenya Power and Lighting Company, the Chemical and construction industries among others.