ABSTRACT
During the daylight hours, a growing plant is warmed by energy in sunlight. At night, when the heat of the sun is temporarily no longer available, the plant will cool. It does this because heat ows spontaneously from a warm object-in this case, the plant-to a cooler one-the air surrounding the plant. The plant loses heat by convection, when currents of warm air rise from the plant, and by radiation, when the plant likely radiates heat as infrared radiation. An energy balance equation applies to this plant, just as to any other system:
− =E E Ein out stored
For this system, Ein is the energy provided by sunlight and Eout is the energy lost by convection and radiation of infrared light.
