Very generally, a portion of the earth's surface defined by relatively uniform temperature characteristics, and usually bounded by selected values of some measure of temperature or temperature effect. All of the following may be considered “temperature zones”: A. Supan's 1879 hot belt, temperate belt, and cold cap; W. Köppen's 1936 tropical rainy climates, temperate rainy climates, snow forest climates, and polar climates; C. W. Thornthwaite's 1931 temperature provinces. It is occasionally used for a vertical subdivision of thermal belts in mountainous terrain. See Also mathematical climate, solar climate.