A new study reveals that the features that make cities unique also at times is responsible for affecting weather and dispersing air pollutants. Researchers say that in comparison with the surroundings, cities can be hot enough such that they influence the weather. They also explained saying that activities like industrial, domestic and transportation results in constant release of heat. Thus after a warm day, the heated concrete surfaces radiate the stored heat long into the night. These phenomena are often responsible for the occurrence of thunderstorm.
In Switzerland , the researchers led by Ecole Polytechnique Federale de Lausanne have shown that the way in which cities are represented in today’s weather and also the air quality models have failed to capture the true magnitude of some important features like the transfer of heat and energy in the lower atmosphere. They also found that for accurately representing cities in weather models, it is essential to sense the processes that atmospheric sensors are unable to sense. The researchers also said that when wind blows over a city, buildings interact with the moving air mass and generate turbulence. This turbulence spreads not only in the atmosphere but also down the streets, resulting in more heat, humidity and pollutants being transported upwards from the ground. At the same time, we find more of the wind’s turbulent energy dissipates between streets, gardens, and other open spaces.
Marco Giometto from EPFL said what we showed in our work is the importance of taking into account the spatial variability of cities, the unique features that make Paris Paris and London London. Giometto said that most city representations used in weather models are based on data obtained from tower measurements made at a particular location within the city, which current models approximate as a rough patch of land. The transport of heat, humidity, or pollutants is then computed using mathematical relationships. These relationships implicitly assume that the city is geometrically regular, which is a stringent assumption.
