metpy.calc.lcl(pressure, temperature, dewpoint, max_iters=50, eps=1e-05)#

Calculate the lifted condensation level (LCL) from the starting point.

The starting state for the parcel is defined by temperature, dewpoint, and pressure. If these are arrays, this function will return a LCL for every index. This function does work with surface grids as a result.

  • pressure (pint.Quantity) – Starting atmospheric pressure

  • temperature (pint.Quantity) – Starting temperature

  • dewpoint (pint.Quantity) – Starting dewpoint

  • max_iters (int, optional) – The maximum number of iterations to use in calculation, defaults to 50.

  • eps (float, optional) – The desired relative error in the calculated value, defaults to 1e-5.



>>> from metpy.calc import lcl
>>> from metpy.units import units
>>> lcl(943 * units.hPa, 33 * units.degC, 28 * units.degC)
(<Quantity(877.563323, 'hectopascal')>, <Quantity(26.7734921, 'degree_Celsius')>)

See also



This function is implemented using an iterative approach to solve for the LCL. The basic algorithm is:

  1. Find the dewpoint from the LCL pressure and starting mixing ratio

  2. Find the LCL pressure from the starting temperature and dewpoint

  3. Iterate until convergence

The function is guaranteed to finish by virtue of the max_iters counter.

Changed in version 1.0: Renamed dewpt parameter to dewpoint

Examples using metpy.calc.lcl#

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