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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 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 ...
Dissolution of the cloud can occur when the process of adiabatic cooling ceases and upward lift of the air is replaced by subsidence. This leads to at least some degree of adiabatic warming of the air which can result in the cloud droplets or crystals turning back into invisible water vapor. [37]
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 .
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 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 ...
Adiabatic process: occurs without loss or gain of energy by heat; ... and extracted from a system by cooling, expansion, or extraction of matter. In mechanics, ...
When this occurs, then any further solar heating of the surface will cause a cloud to form topping the well-mixed boundary layer, and the level at which this occurs is called the CCL. If the boundary layer starts off with a stable temperature profile (that is, with a lapse rate less than the dry adiabatic lapse rate), then the CCL will be ...