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el#

metpy.calc.el(pressure, temperature, dewpoint, parcel_temperature_profile=None, which='top')[source]#

Calculate the equilibrium level.

This works by finding the last intersection of the ideal parcel path and the measured environmental temperature. If there is one or fewer intersections, there is no equilibrium level.

Parameters:

  • pressure (pint.Quantity) – Atmospheric pressure profile. This array must be from high to low pressure.

  • temperature (pint.Quantity) – Temperature at the levels given by pressure

  • dewpoint (pint.Quantity) – Dewpoint at the levels given by pressure

  • parcel_temperature_profile (pint.Quantity, optional) – The parcel’s temperature profile from which to calculate the EL. Defaults to the surface parcel profile.

  • which (str, optional) – Pick which EL to return. Options are ‘top’, ‘bottom’, ‘wide’, ‘most_cape’, and ‘all’. ‘top’ returns the lowest-pressure EL, default. ‘bottom’ returns the highest-pressure EL. ‘wide’ returns the EL whose corresponding LFC is farthest away. ‘most_cape’ returns the EL that results in the most CAPE in the profile.

Returns:

  • pint.Quantity – EL pressure, or array of same if which=’all’

  • pint.Quantity – EL temperature, or array of same if which=’all’

Examples

>>> from metpy.calc import el, dewpoint_from_relative_humidity, parcel_profile
>>> from metpy.units import units
>>> # pressure
>>> p = [1008., 1000., 950., 900., 850., 800., 750., 700., 650., 600.,
...      550., 500., 450., 400., 350., 300., 250., 200.,
...      175., 150., 125., 100., 80., 70., 60., 50.,
...      40., 30., 25., 20.] * units.hPa
>>> # temperature
>>> T = [29.3, 28.1, 23.5, 20.9, 18.4, 15.9, 13.1, 10.1, 6.7, 3.1,
...      -0.5, -4.5, -9.0, -14.8, -21.5, -29.7, -40.0, -52.4,
...      -59.2, -66.5, -74.1, -78.5, -76.0, -71.6, -66.7, -61.3,
...      -56.3, -51.7, -50.7, -47.5] * units.degC
>>> # relative humidity
>>> rh = [.85, .65, .36, .39, .82, .72, .75, .86, .65, .22, .52,
...       .66, .64, .20, .05, .75, .76, .45, .25, .48, .76, .88,
...       .56, .88, .39, .67, .15, .04, .94, .35] * units.dimensionless
>>> # calculate dewpoint
>>> Td = dewpoint_from_relative_humidity(T, rh)
>>> # compute parcel profile temperature
>>> prof = parcel_profile(p, T[0], Td[0]).to('degC')
>>> # calculate EL
>>> el(p, T, Td, prof)
(<Quantity(111.739463, 'hectopascal')>, <Quantity(-76.3112792, 'degree_Celsius')>)

See also

parcel_profile

Notes

Only functions on 1D profiles (not higher-dimension vertical cross sections or grids). Since this function returns scalar values when given a profile, this will return Pint Quantities even when given xarray DataArray profiles.

Changed in version 1.0: Renamed dewpt parameter to dewpoint

Examples using metpy.calc.el#

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