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An adiabatic process (adiabatic from Ancient Greek ἀδιάβατος (adiábatos) ' impassable ') is a type of thermodynamic process that occurs without transferring heat between the thermodynamic system and its environment. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work and/or mass flow.
The saturated adiabatic lapse rate (SALR), or moist adiabatic lapse rate (MALR), is the decrease in temperature of a parcel of water-saturated air that rises in the atmosphere. It varies with the temperature and pressure of the parcel and is often in the range 3.6 to 9.2 °C/km (2 to 5 °F/1000 ft ), as obtained from the International Civil ...
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. [ 1 ] : 162 As the air mass gains altitude it quickly cools down adiabatically , which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation .
Adiabatic process: occurs without loss or gain of energy by heat; Isenthalpic process: occurs at a constant enthalpy; Isentropic process: a reversible adiabatic process, occurs at a constant entropy; Isobaric process: occurs at constant pressure; Isochoric process: occurs at constant volume (also called isometric/isovolumetric)
There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, and evaporative cooling. Adiabatic cooling occurs when air rises and expands. [20] The air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain (orographic lift).
The main mechanism behind this process is adiabatic cooling. [13] As the air is cooled to its dew point and becomes saturated, water vapor normally condenses to form cloud drops. This condensation normally occurs on cloud condensation nuclei such as salt or dust particles that are small enough to be held aloft by normal circulation of the air ...
An adiabatic process is a process in which there is no matter or heat transfer, because a thermally insulating wall separates the system from its surroundings. For the process to be natural, either (a) work must be done on the system at a finite rate, so that the internal energy of the system increases; the entropy of the system increases even ...
Air at the top of a mountain is usually colder than the air in the valley below, but the arrangement is not unstable: if a parcel of air from the valley were somehow lifted up to the top of the mountain, when it arrived it would be even colder than the air already there, due to adiabatic cooling; it would be heavier than the ambient air, and ...