Summertime cloud-to-ground lightning activity around major Midwestern urban areas

Cloud-to-ground lightning flash data collected by the National Lightning Detection Network were analyzed in and around 16 central US cities for the period 1989-92. Lightning data are well suited to study storm activity in and around large urban areas since their continuity and coverage in space and time is superior to historical, spatially limited records of thunderstorm activity. A number of possible urban-related causal factors were examined including effects of increased urban concentrations of cloud condensation nuclei, urban population and size, and the presence of distinct topographic features in and around the cities. Various factors, physical and anthropogenic, appeared to interact in diverse ways to account for changes in lightning flash frequency. -from Author