What roles do trees play in the “urban heat island” phenomenon?
Basically there are two important roles tree canopies play: • The forest canopy is very efficient in dissipating the solar energy received by transpiring water from leaf surfaces which cools the air by taking “heat” from the air to evaporate the water. • In shading surfaces like asphalt, roofs, and concrete parking lots which prevents initial heating and storage of heat. An example of the kind of “data” obtained from the NASA scanner is an image from the area around Madison Square Mall (photo) in Huntsville. Warmer temperatures are represented by lighter shades of gray & white and the darker shades as the cooler temperatures. The average temperature was 45.1 °C compared with a nearby forested area at 29.6 °C. A spot check of day temperatures around the Mall shows that in the middle of the parking lot temperatures reach about 48.8 °C . However, a “tree island”, a small planter containing a couple of trees in the parking lot is only 31.6 °C. So, even a small area of tree coverage surroun
