lcl()
definition thermo_parcel_path(vector t_profile, vector td_profile, vector p_profile, definition start_condition)
definition thermo_parcel_path(thermo_profile profile, definition start_condition)
Computes the path of an ascending thermodynamic parcel with the given start condition for the given vertical profile. It returns a definition suitable for plotting all the details of the parcel path into a thermodynamic diagram. The vertical profile is either specified as a set of vectors where:
t_profile: the temperature profile (in K or °C)td_profile: the dew point temperature profile (in K or °C)p_profile: the pressure profile (in Pa or hPa)
or as a vertical profile where:
profile: the result of a vertical profile extraction from GRIB or BUFR with the thermo_grib() or thermo_bufr() functions, respectively.
The start_condition is a definition that can specify these four different modes:
Surface
The parcel is started from the surface, i.e. the lowest point of the profile. The format is as follows:
(mode: 'surface')
Custom
The parcel is started from the 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 from the mean temperature, dew point and pressure of a given pressure layer. The format is as follows:
(mode: 'mean_layer', p_top: layer_top, p_bottom: layer_bottom )
Please note that when p_bottom is omitted the layer starts at the surface.
Most unstable
The parcel is started 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 of the parcel that results in the highest CAPE value defines the most unstable start condition.
(mode: 'most_unstable',
p_top: layer_top,
p_bottom: layer_bottom )
Please note that when p_bottom is omitted the pressure layer starts at the surface.
| Mode | Definition |
|---|---|
Surface The parcel is started from the surface, i.e. the lowest point of the profile. | |
Custom The parcel is started from the given temperature, dewpoint and pressure. | (mode: 'custom', t: start_temperature, td: start_dewpoint, p: start_pressure) |
Mean layer The parcel is started from the mean temperature, dew point and pressure of a given pressure layer. Please note that when | (mode: 'mean_layer', p_top: layer_top, p_bottom: layer_bottom ) |
Most unstable The parcel is started 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 staring position of the parcel that results in the highest CAPE value defines the most unstable start condition. Please note that when | (mode: 'most_unstable', p_top: layer_top, p_bottom: layer_bottom ) |
The result is a definition with the following members:
- path: the path of the parcel. It is 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