13 articles
Convective available potential energy
Convective available potential energy (CAPE) is a measure, in joules per kilogram, of the buoyant energy available to accelerate rising air, widely used to gauge thunderstorm potential.
Equivalent potential temperature
Equivalent potential temperature, or theta-e, is the temperature an air parcel would reach if all its water vapor condensed and it were brought adiabatically to 1000 mb.
Frost point
The frost point is the temperature to which air must be cooled at constant pressure for water vapor to deposit as frost instead of condensing as dew.
Isentropic surface
An isentropic surface is a surface in the atmosphere on which potential temperature, equivalently entropy, is everywhere equal, so adiabatic air parcels slide along it.
Mixing ratio
Mixing ratio is the ratio of the mass of water vapor to the mass of dry air in moist air, usually quoted in grams of vapor per kilogram.
Moist static energy
Moist static energy (MSE) is a thermodynamic quantity of moist air, the sum of enthalpy, gravitational potential energy, and latent heat of water vapor, conserved in reversible adiabatic processes and widely used to study tropical convection.
Potential temperature
Potential temperature (symbol θ) is the temperature a dry air parcel would have if brought adiabatically, without heat exchange, to a standard pressure, typically 1000 hPa.
Precipitable water
Precipitable water (PW, also precipitable water vapor, PWV) is the total water vapor in a vertical atmospheric column, expressed as the depth of liquid water if fully condensed.
Saturation vapor pressure
Saturation vapor pressure is the pressure of a vapor in equilibrium with its liquid or solid at a given temperature, rising rapidly as temperature increases.
Static stability
Static stability, also called hydrostatic or vertical stability, is the tendency of a fluid at rest, such as the atmosphere, to resist or favor vertical displacement through buoyancy.
Virtual temperature
Virtual temperature, also called density temperature, is the temperature dry air would have at the same pressure and density as a given sample of moist air.
Water activity
Water activity (aw) is the ratio of a substance's water vapor pressure to that of pure water, measuring free moisture. Key in food preservation and microbial limits: FDA threshold 0.85, C. botulinum minimum about 0.93.
Wet-bulb potential temperature
Wet-bulb potential temperature, written θw, is the temperature an air parcel reaches after adiabatic cooling to saturation and moist-adiabatic transport to 1000 mb, conserved in adiabatic processes.