Variability of meteorological parameters within cities:
This contribution discusses the differential microclimates within built-up areas, i.e. within street canyons, city squares but also local-scale differences between urban districts, parks and urban water bodies. The differences in radiation, air temperature and humidity, thermal stress and air pollution exposure are explained by the energy balance, the water balance and the strength of and proximity to emissions.
Instead of directly modifying temperature, humidity or air quality, sustainable urban planning and architecture must modify the underlying energy balance of the urban surface, water balance and control emissions in a way that existing, natural resources are used efficiently, the stress on the population in extreme weather conditions is reduced and populations are protected against atmospheric hazards in cities.