1) Process in which heat energy is transported through a medium, usually a gas or liquid. An example, in the atmosphere occurs when warm air with a lower density experiences an upward force until it cools and its density matches the surrounding air, generally termed convection cells.
source: [A Field Guide to the Atmosphere; Day, John and Schaefer, Vincent; 65-74; 1981; Houghton Mifflin; Boston.] [Dictionary of Astronomy, Space and Atmospheric Phenomena; Tuer, David; pg. 56; 1979; Van Nostrand Reinholds; NY.]