Why is it so hot at night in some cities?

(CNRS) 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 2 (CNRS/MIT) and CINaM (CNRS/AMU) have shown that the determining factor is how cities are structured: more organized cities trap more heat. Cities that are less organized shed heat easily. The team's findings suggest new directions to explore for optimal urban planning and energy management.