ABSTRACT
The presence of urban trees and forest affects all atmospheric variables; those that show the greatest evidence are the air temperature, surface temperatures and mean radiant temperature. This chapter presents knowledge concerning the effects of urban trees and forests on urban microclimate variables and human thermal comfort. Vegetation is commonly considered a factor in climate control in the urban environment. The cooling effect of vegetation has been well-documented worldwide, and it is primary due to the combined effect of evapotranspiration and shade. The structural and morphological characteristics of a tree or a forest modify the energy fluxes, especially the radiation fluxes, resulting in a unique microclimate. Besides the modified radiation fluxes, the urban forest microclimate includes specific features such as a weaker diurnal cycle of Ta, increased relative humidity (RH), and reduced wind speed (v), which can be important for several issues and applications.
