Chapter 1. H eatwave Resilience in the City of Bucharest Urban Heat Island, the Cause of Rising Temperatures Surfaces covered with concrete, bitumen, asphalt, or other materials, alter the temperature by a few degrees, proportionally to the size of the surface. Cities the same size as Bucharest(a few hundred hectares) may increase the ambient temperature by 5-6⁰C as compared to the surrounding region, thus generating a so-called“urban heat island”. Built surfaces in cities retain a greater amount of heat, while a lack of vegetation reduces evapotranspiration and the natural shading effect. Moreover, rainwater drains quickly and does not maintain soil humidity, while human activities release additional heat. The buildings and the urban infrastructure enhance surface roughness, hindering air circulation, and air pollution intensifies the greenhouse effect. All these factors contribute to an increase in temperatures inside the city, proportionally to their respective level of influence. The size of the city, the number of inhabitants, and economic development are other factors that contribute to amplifying the urban heat island effect. Over 50% of Bucharest’s surface is anthropogenically modified through buildings, roads, industrial areas, and other forms of landscaping. Monitoring Air and Surface Temperature in Bucharest The national network managed by the National Meteorological Administration uses three weather stations to monitor air temperature. The stations are installed under standard conditions recommended by the World Meteorological Administration(WMO): București-Băneasa(located in the northern part of the capital), Afumați(northeast), and Filaret(located centrally, around Carol Park). In addition, 6 sensors monitor the air temperature in urban environments (Masca Theatre, Sf. Nicolae Special School, Grigore Ghica Voievod Gymnasium School no.30, Cervantes High School, Paradisul verde Kindergarten, and Mihai Bravu High School), all managed by the National Meteorological Administration. An important source of information, currently insufficiently tapped into, are Theoretical model of an urban heat island The air temperature is higher in the central areas of a city compared to the outskirts and surrounding areas Figure 1 6 Friedrich-Ebert-Stiftung e.V. Source: https://community.wmo.int/en/activity-areas/urban/urban-heat-island