Dev Niyogi on urban sprawl and storm intensity

Tornadoes are usually drawn to wide-open spaces. That’s according to climatologist Dev Niyogi of Purdue University. So Dev Niyogi wondered…

Dev Niyogi: Why did we get a tornado in an urban region like Atlanta?

Niyogi has been studying the tornado that struck Atlanta, Georgia in early 2008 and caused over $200,000,000 in damage. He said it started as a thunderstorm, but as it moved toward the city, it passed through what Niyogi described as a ‘mosaic’ of urban sprawl – moist agricultural areas interspersed with dry, hot paved regions.

Dev Niyogi: It’s going over a wet region and it gets its moisture and all the juice it needs, then it gets over a warmer region and gets all the heat it needs, and gets even more intensified.

Based on satellite data, Niyogi believes the storm developed into a full-blown tornado when it reached the city and mixed with Atlanta’s dry heat.

Dev Niyogi: The urban region is warmer than the surrounding region by about 5-10 degrees Celsius, at times.

Niyogi said this understanding could benefit urban planning and development across the U.S., since many cities have a patchwork of sprawl – and heat – like Atlanta’s.

Dev Niyogi: So even though we cannot alter every thunderstorm that comes our way, we can certainly use some science that is evolving now to see what kind of buffers ought to be developed around the cities to reduce the threats of severe thunderstorms.

He said that buffer could be as simple as a reforestation zone.

Niyogi’s research could also help urban planners decide in what direction to expand a city.

Dev Niyogi: A specific example we have right now is we’re studying the Indianapolis, Indiana region and we are seeing that when a city is made bigger than it is right now, the thunderstorms actually start getting deflected away from a city. So one could start thinking In what direction to expand the city.

Our thanks to:
Dr. Dev Niyogi is an Assistant Professor with joint appointment in the Departments of Agronomy and Earth and Atmospheric Sciences at Purdue University . He is also the State Climatologist for Indiana and the Director of the Indiana State Climate Office.