A study that assessed the impact of urban land use on the initiation of thunderstorms from 1997 to 2013 in the humid subtropical region of the southeast United States found that so-called isolated convective initiation events occur more often over the urban area of Atlanta compared with its surrounding rural counterparts. The findings confirm that human-induced changes in land cover in tropical environments lead to more thunderstorm initiation events.
The thunderstorm formation risk for Atlanta is greatest during the late afternoon and early evening in July and August. Greater thunderstorm initiation counts over and downwind of Atlanta suggest that prevailing wind direction also influences the location of these events. Moreover, thunderstorm initiation events over the city are significantly higher on weekdays compared with weekend days, suggesting that increased aerosol levels from commuters may play a role.
"Urbanization has led to more thunderstorm initiation events than would have occurred over natural vegetation. These events, which are an illustration of anthropogenic climate change at the local scale, can produce a number of dangerous weather hazards including lightning, strong winds, hail, and flash floods, often with little or no warning," said Alex Haberlie, lead author of the study published in the Quarterly Journal of the Royal Meteorological Society. "City planners, meteorologists, and citizens who live in or near a large urban area should be aware of this increased risk."