An exponential ratio of two values of this quantity is used to calculate a [emphasize] different quantity in the Tetens formula. An integral proportional to the relative difference in the virtual form of this quantity between an air parcel and its environment gives the CAPE, which is often measured on diagrams named for having lines of this quantity at 45 degrees, or “skewed.” This quantity’s negative derivative with respect to (10[1])altitude gives (10[1])the lapse (10[2])rate, which is (10[2])negative for inversion layers that trap pollutants. An instrument wrapped in moistened cloth is used to measure this (-5[1])quantity’s “wet bulb” form. The (-5[1])value for this quantity that results in a relative humidity of 100 percent is called the dew point. For 10 points, name this quantity that a weather forecast (10[1])might report in degrees Celsius. (10[2])■END■