Aero package is a term from the theoretical meteorology and referred to a certain air quantity or an air volume that is large enough to over state variables such as temperature , pressure , density and humidity are described to be able to, but again is small enough to fit in to be considered infinitesimal in mathematical treatment . It is therefore a theoretical concept that is intended to be able to correctly describe small-scale effects in a narrowly limited space, although there is no such limitation.
The term is mainly used when describing adiabatic vertical or advective processes of atmospheric dynamics. It is particularly suitable from a didactic point of view, as it is easier to imagine a certain amount of air and its rise in the atmosphere, for example, than to grasp the merging dynamics of entire air masses .
Before a vertical displacement, the air package has the same density or temperature as the surrounding air. No heat is added to or withdrawn from it, that is, it moves adiabatically , and then no mixture with the surrounding air occurs ( laminar flow ).
|Hydrostatic equilibrium on graph paper|
The equilibria behave analogously for the wet adiabatic ascent, in which the air parcel rises wet adiabatically, i.e. at about 0.5 ° C per 100 m. A distinction is also made here between moisture-stable and moisture-unstable stratification.
In the special case of the conditionally unstable atmosphere stratification, the atmosphere is stable with dry adiabatic ascent, but unstable with wet adiabatic ascent.
- Guide for training in DWD No. 1, German Weather Service .