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definition lifted_condensation_level(t: number t, td: number td, p: number p)

Computes the Lifted Condensation Level (LCL) of a parcel ascending from a given temperature, dewpoint and pressure, where

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The result is a definition with two members: t and p, containing the temperature and pressure of the LCL, in K and Pa units, respectively. On error or if the LCL does not exist nil is returned.


number mixing_ratio(q: number q)

Computes the mixing ratio from the given specific humidity, where

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number mixing_ratio_from_vapour_pressure(p: number p, e: number e)

Computes the mixing ratio from the given (total) pressure and vapour pressure, where

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number potential_temperature(t: number t, p: number p)

Computes the potential temperature for a given temperature and pressure, where

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The result is the potential temperature in K units. On error  nil is returned.

number relative_humidity(number t, number q, number p)

Computes the relative humidity for a given temperature, specific humidity and pressure, where

    • t: temperature (K)
    • q: specific humidity (kg/kg)
    • p: pressure (Pa)

The result is the relative humidity in the range of [0, 1]. On error nil is returned. The computation is based on the following formula:

Mathdisplay
r = \frac{e(q, p)}{e_{sat}(t)}

where e is the vapour pressure and esat is the saturation vapour pressure.


fieldset relhum(...)

Extract vertical profiles from BUFR data in a suitable format suitable for thermodynamic diagrams (defined by Thermo View). This is a Metview icon function, for detailed documentation please see Thermo Data.

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number saturation_mixing_ratio(t: number t, p: number p)

Computes the saturation mixing ratio for a given temperature and pressure, where

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number saturation_vapour_pressure(t: number t)

Computes the saturation vapour pressure for a given temperature, where

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number temperature_from_potential_temperature(th: number th, p: number p)

Computes the temperature for a given potential temperature and pressure, where

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definition thermo_parcel_path(t: vector t, td: vector td, p: vector p,   options: definition options)

definition thermo_parcel_path(profile: netcdf profile,   options: definition options)

Computes the path of an ascending thermodynamic parcel with the given start condition for the given vertical profile. It returns a definition containing all the data to plot parcel path, buoyancy areas and related data into a thermodynamic diagram. The vertical profile is either specified as a set of vectors where:

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    • path: path of the parcel. It is itself a definition with two members: t and p, each containing a list of values.
    • area: positive and negative buoyancy areas between the parcel path and the profile. It is a list of definitions describing the areas.
    • cape: value of the CAPE (Convective Available Potential Energy)  (J/kg)
    • cin: value the CIN (Convective Inhibition) (J/kg)
    • lcl: Lifted Condensation Level. It is a definition with two members: t and p. If no LCL exists it is set to nil.
    • lfc: Level of Free Convention. It is a definition with two members: t and p. If no LFC exists it is set to nil.
    • el: Equilibrium Level. It is a definition with two members: t and p. If no EL exists it is set to nil.
    • top: Cloud Top Level. It is a definition with two members: t and p. If no TOP exists it is set to nil.
    • start: start conditions of the parcel with four members: mode, t, td and p.


number vapour_pressure(q: number q, p: number p)

Computes the vapour pressure for a given specific humidity and pressure, where

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