In summer, green spaces are particularly useful in modifying the environment during the late afternoon, when the buildings are very hot inside. Strong local winds can modifiy the temperature distribution described above. Usually winds in towns are moderate because of the number and range of obstacles they face. However, a few configurations such as long straight avenues or multi-storey buildings can cause significant air circulation. Tall buildings rising above low-rise building can create strong turbulent wind conditions on the ground as the air is brought down from high levels.
Strong winds can flow through gaps at the base of tall buildings.
To protect pedestrians from this, the turbulent flow has to be prevented from descending to street level, for example by modifying the building form or by using wide protective canopies. In semi-open areas, adjacent buildings can be used as protective screens against some winds. 6.2 Urban Heat Island Visit any city on a hot summer day, and you will feel waves of blistering heat emanating from roads and dark buildings. Stay in the city past nightfall, and you will notice that the streets are still radiating heat, while surrounding rural areas are rapidly cooling. People also believe there is a direct link between global warming and urban heat islands.