AYESHA RASCOE, HOST:
If you think it rains a lot in your city, it's not your imagination. Researchers at the University of Texas at Austin found that 60% of urban areas get more rain than their rural surroundings.
(SOUNDBITE OF SONG, "ANOTHER RAINY DAY IN NEW YORK CITY")
CHICAGO: (Singing) Another rainy day in New York City - softly sweet, so silently it falls, as cross town traffic crawls...
RASCOE: Dev Niyogi is a professor at UT's Jackson School of Geo Sciences. He's also co-author of the study that was published this month in the proceedings of the National Academy of Sciences. And he joins us now. Welcome to the program.
DEV NIYOGI: Thank you.
RASCOE: What's your explanation for why it would rain more often over cities?
NIYOGI: When you have the cities heating up the atmosphere, that is how we see in the context of the urban heat island. It is not just the changes in temperature that matter. You also have the humidity in the city. You sometimes have more pollutants coming because of the cars and anthropogenic activity, which could create more aerosols in the atmosphere. Aerosols have the ability, just like, you know, your salt shaker might absorb moisture, and you're not able to take the salt out. They have an ability to attract the moisture from the atmosphere and retain it. And so now you have an atmosphere which is warm and juicy with a lot of moisture. So it's a complex interaction between the dynamics, the kind of building you have, whether they're tall buildings, whether there's sprawled out buildings, and the type of land use that you have around the city.
RASCOE: Now, is part of what you're seeing due to climate change, or is this a totally separate phenomenon?
NIYOGI: It's very difficult to separate out weather and climate because the weather we experience today is not something that has just magically happened. So when you have a warming in the atmosphere, you have the ability of the atmosphere to hold more moisture. Now you suddenly have a potential for creating more rain. What cities do is that they reorient where it would rain, and they also have the ability to squeeze out the rain from the clouds at a specific locations, if you will, and create more intense storms while the large-scale environment is creating the storm in the first place.
RASCOE: The cities that are getting a lot of rain - what are some of the problems that they're facing?
NIYOGI: Right. When we have rains, many a times, they can be quite a menace. If they're coming during office hours or during school times, then they can be snarling your traffic and creating a traffic jam. In more extreme scenarios, this could be creating pockets where you have flooding and houses getting affected. You could also have ecological or health issues associated where there could be exaggerated runoff in which some of the rains can then get into your water flow and make the streams have some etipication, or some sort of an impact on that.
RASCOE: Can you talk about what architects and urban planners need to keep in mind?
NIYOGI: Right. So when we think about cities and we say we are going to design our cities for the future, I think we can start planning how do we either attract or deflect the rains as we want with the cities? Let us also start looking, what can we do different that can help us recharge our water resources, or what can we do different, that can reduce the risk associated with flooding?
RASCOE: That's Dev Niyogi. He is a professor who studies climate in cities at the University of Texas at Austin. Thank you so much for joining us.
NIYOGI: You're very welcome.
(SOUNDBITE OF SONG, "ANOTHER RAINY DAY IN NEW YORK CITY")
CHICAGO: (Singing) Another rainy day in New York City, la la la la la la... Transcript provided by NPR, Copyright NPR.
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