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profile: the result of a vertical profile extraction from GRIB or BUFR with the thermo_grib() or thermo_bufr() functions, respectively.
The There are four different modes to specify the a parcel's start_condition is (as a definition specifying the release can specify these four different modes):
Surface
The parcel is started ascends from the surface, i.e. the lowest point of the profile. The format is as follows:
(mode: 'surface')
Custom
The parcel is started ascends from the a given temperature, dewpoint and pressure. The format is as follows:
(mode: 'custom', t: start_temperature, td: start_dewpoint, p: start_pressure)
Mean layer
The parcel is started ascends from the mean temperature, dew point and pressure of a given pressure layer. The format is as follows:
...
Please note that when p_bottom is omitted the layer starts at the surface.
Most unstable
The parcel is started ascends from the most unstable condition. To determine this, a parcel is started from all the points along the profile in the specified pressure layer. The start position level of the parcel that results in the highest CAPE value defines will define the most unstable start condition. The format is as follows:
...
The function returns a definition with the following membersseveral members to describe all th parameters related to the parcel's ascend. These are as follows:
- path: the path of the parcel. It is itself a definition with two members: t and p, each containing a list of values.
- area: the positive and negative buoyancy areas between the parcel path and the profile. It is a list of definitions describing the areas.
- cape: the value of the CAPE (Convective Available Potential Energy) (J/kg)
- cin: value the CIN (Convective Inhibition) (J/kg)
- lcl: the Lifted Condensation Level. It is a definition with two members: t and p. If no LCL exists it is set to nil.
- lfc: the Level of Free Convention. It is a definition with two members: t and p. If no LFC exists it is set to nil.
- el: the Equilibrium Level. It is a definition with two members: t and p. If no EL exists it is set to nil.
- top: the Cloud Top Level. It is defined by the pressure level where the parcel parcel. It is a definition with two members: t and p. If no TOP exists it is set to nil.