# showalter_index#

metpy.calc.showalter_index(pressure, temperature, dewpoint)[source]#

Calculate Showalter Index.

Showalter Index derived from [Galway1956]:

$SI = T500 - Tp500$

where:

• $$T500$$ is the measured temperature at 500 hPa

• $$Tp500$$ is the temperature of the parcel at 500 hPa when lifted from 850 hPa

Parameters:
Returns:

pint.Quantity – Showalter index

Examples

>>> from metpy.calc import dewpoint_from_relative_humidity, showalter_index
>>> 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 the showalter index
>>> showalter_index(p, T, Td)
<Quantity([0.48421285], 'delta_degree_Celsius')>


## Examples using metpy.calc.showalter_index#

Sounding Calculation Examples

Sounding Calculation Examples