FIGURE3.12/mean annual total heating degree-days in thousands of f ;where the number 4on the map represents 4000(base 65 f ) FIGURE3.13 mean annual total cooling degree-days in thousands of f Where the number 1on the map represents 1000(base 65 f) AIR TEMPERATURE AND HUMAN COMFORT probably evreyone realizes that the same air temperature can feel differently on different occasions. For example a temperature of 20 c (68 f) on a clear windless March afternoon in new york city can almost feel balmy after a long hard winter .Yet this same temperature may feel uncomfortably cool on a summmmer afternoon in a stiff breeze. The human bodys perception of temperature ob-viously changes with varying atmospheric conditions The reason for these changes is related to how we ex-change heat energy with our environment. The body stabilizes its temperature primarily by converting food in to heat (metabolism).To maintain a constant temperature the heat produced and absorbed*