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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 definition can specify these four different modes:

Mode Definition

Surface

The parcel is started from the surface, i.e. the lowest point of the profile.

(mode: 'surface')

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 p_bottom is omitted the layer starts at the surface.

(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 a specified pressure layer. The staring position of the parcel resulting in the highest CAPE value define the most unstable start condition.

Please note that when p_bottom is omitted the pressure layer starts at the surface.

(mode: 'most_unstable',
p_top: layer_top,
p_bottom: layer_bottom )

The result