Thermal Belt

… (also called Isothermal Belt), verdant zone largely in Polk and Rutherford Counties—though to a lesser extent also in Caldwell, Mitchell, and other mountain counties—in which on certain cool nights, the temperature may be 20° or more higher on the slope of a mountain than at the base. In these areas, fruit growing is a successful undertaking, and at Tryon (Polk County) the thermal belt has contributed to resort prosperity. The thermal belt was first described by Silas McDowell in 1858.