Tag : Humidity

    Humidity Might Increase Heat Risk In Urban Climates: Study

    Heat Risk In Urban Climates
    Inam Ansari
    April27/ 2023

    Washington: As temperatures throughout the world hit record highs, cities are experiencing unusual heat stress. Cities are often warmer and drier than surrounding rural terrain. However, in the Global South, there is an extra complicating factor: urban humid heat. A new study, led by Yale School of the Environment scientists and published in Nature, investigated the combined effect of temperature and humidity on urban heat stress using observational data and an urban climate model calculation. Researchers found that the heat stress burden is dependent on local climate and a humidifying effect can erase the cooling benefits that would come from trees and vegetation. "A widely held view is that urban residents suffer more heat burden than the general population owing to the urban heat island phenomenon. This view is incomplete because it omits another ubiquitous urban microclimate phenomenon called the urban dry island -- that urban land tends to be less humid than the surrounding rural land," says Xuhui Lee, Sara Shallenberger Brown Professor of Meteorology, who directed the study. "In dry, temperate, and boreal climates, urban residents are actually less heat-stressed than rural residents. But in the humid Global South, the urban heat island is dominant over the urban dry island, resulting in two to six extra dangerous heat stress days per summer." Lee and YSE doctoral student Keer Zhang, lead author of the study, say they were motivated to investigate the issue for several reasons: a large percentage of the global population lives in urban areas; many people in informal urban settlements do not have access to air conditioning; and the problem is going to get worse as temperatures rise and more people move to cities. About 4.3 billion ...

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