Городские мегаполисы усиливают грозы и меняют погодные условия

A recent study out of Texas A&M found that cities have a role in shaping weather patterns. The findings, published in the science journal Nature earlier this year, show thunderstorms are more likely to develop and strengthen over large urban cities like Dallas and Houston, while cold fronts potentially weaken as they move across urban areas. “Cities appear to have an impact on rainfall systems and that impact depends on the type of system,” said state climatologist John Nielsen-Gammon, a co-author of the study. The key way cities affect weather is through temperature, Nielsen-Gammon said. Urban areas tend to hold on to heat longer because of the density of pavement and large buildings, known as the “heat island” effect. “That presumably accounts for how it is that we saw more thunderstorms developing over cities than over the surrounding countryside,” Nielsen-Gammon said. “[The air is] just a little bit more unstable over the cities.” Researchers used radar data of more than 40,000 storms recorded between 1995 and 2017 to put together a three-dimensional picture of the atmosphere around Austin, Houston, Dallas and San Antonio. “All four cities exhibit a higher frequency of isolated storms compared with their rural counterparts, with 7–16% increases in three inland cities,” read the study. In the Dallas area specifically, Nielsen-Gammon said researchers found that heat trapped in paved areas tends to amplify the heat island effect. “You've got these places where there's lots of evaporation in the rural areas with the reservoirs and the farms and so forth compared to the urban areas, where things tend to be a bit drier,” Nielsen-Gammon said. He added that continued population growth in major cities like Dallas and Houston only amplify the intensity of certain storms. “We're able to actually see that different types of storms are actually affected differently,” Nielsen-Gammon said. “That explains some of the different results that have appeared in previous studies.” Results from the study can help improve weather forecasting, flood mitigation and emergency preparedness in major cities. Pablo Arauz Peña is KERA’s growth and infrastructure reporter. Got a tip? Email Pablo at [email protected]. KERA News is made possible through the generosity of our members. If you find this reporting valuable, consider making a tax-deductible gift today. Thank you.