The Air-Conditioning Factor
An established tree draws over 100 litres of water each day from deep in the soil to cool its leaves. However, as this water emerges from the leaf, energy is drawn from the surrounding air to change the liquid to gas (the latent heat factor). This is the same process our refrigerators use to cool our food (and perspiration uses to cool our bodies). So not only does a tree’s canopy block and absorb sunlight, it also has the ability to evaporate water which literally draws heat out of the atmosphere. This means that trees throughout cities cool the air and thus lower the air temperature in our cities.