]> The environmental lapse rate of temperature in an atmosphere in which the density is constant with height (homogeneous atmosphere), equal to g/R, where g is the acceleration of gravity and R the gas constant. The temperature that a parcel would have if brought adiabatically and reversibly from its initial state to a standard reference pressure, typically 100 kPa. The temperature an air parcel would have if cooled from its initial state adiabatically to saturation, and thence brought to 1000 mb by a moist-adiabatic process. A process lapse rate of temperature, the rate of decrease of temperature with height of a parcel of dry air lifted by a reversible adiabatic process through an atmosphere in hydrostatic equilibrium. The rate of decrease of temperature with elevation Analogous to convective available potential energy, except that it is related to the negative buoyancy associated with evaporative cooling of liquid water within a sinking cloudy air parcel. A measure of the mean thermodynamic stability in a layer beneath 700 mb. Level of free convection A region of negative buoyancy below an existing level of free convection (LFC) where energy must be supplied to the parcel to maintain its ascent. The energy needed to lift an air parcel vertically and pseudoadiabatically from its originating level to its level of free convection (LFC). A line of constant potential temperature on a thermodynamic diagram. Adiabatic Atmosphere A model atmosphere characterized by a dry-adiabatic lapse rate throughout its vertical extent. Ascending air flow caused by mountains. Mechanisms that produce the lifting fall into two broad categories: 1) the upward deflection of horizontal larger-scale flow by the orography acting as an obstacle or barrier; or 2) the daytime heating of mountain surfaces to produce anabatic flow along the slopes and updrafts in the vicinity of the peaks. The state of a layer of unsaturated air when its lapse rate of temperature is less than the dry-adiabatic lapse rate but greater than the moist-adiabatic lapse rate. The state of a layer of unsaturated air when its lapse rate of temperature is less than the dry-adiabatic lapse rate but greater than the moist-adiabatic lapse rate. A temperature inversion (temperature rising with height) in the atmosphere, encountered upon vertical ascent through a sloping front (or frontal zone). In meteorology, a departure from the usual decrease or increase with altitude of the value of an atmospheric quantity; also, the layer through which this departure occurs (the inversion layer), or the lowest altitude at which the departure is found (the base of the inversion). state of a layer of atmosphere when it has superadiabatic lapse rate of temperature Absolute Instability Dry Adiabatic Process 1. An adiabatic process in a hypothetical atmosphere in which no moisture is present. 2. An adiabatic process in which no condensation of its water vapor occurs and no liquid water is present. A moist-adiabatic process in which the liquid water that condenses is assumed to be removed as soon as it is formed, by idealized instantaneous precipitation.