Why is it so hot at night in some cities?

During the nighttime, it is hotter in the city than in nearby suburbs or the countryside. But just how much hotter differs between cities. Researchers from the MSE2 (CNRS / MIT) international joint research laboratory and the Centre Interdisciplinaire des Nanosciences de Marseille (CNRS / Aix-Marseille University)1 have shown that the determining factor is how cities are structured: more organized cities, like many in North America with straight and perpendicular streets, trap more heat. Conversely, cities that are less organized, like those founded long ago, shed heat easily. The team's findings, published in Physical Review Letters (March 9, 2018), suggest new directions to explore for optimal urban planning and energy management.