Note
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Dewpoint and Mixing Ratio#
Use functions from metpy.calc as well as pint’s unit support to perform calculations.
The code below converts the mixing ratio value into a value for vapor pressure assuming both 1000mb and 850mb ambient air pressure values. It also demonstrates converting the resulting dewpoint temperature to degrees Fahrenheit.
import metpy.calc as mpcalc
from metpy.units import units
Create a test value of mixing ratio in grams per kilogram
mixing = 10 * units('g/kg')
print(mixing)
Out:
10.0 gram / kilogram
Now throw that value with units into the function to calculate the corresponding vapor pressure, given a surface pressure of 1000 mb
e = mpcalc.vapor_pressure(1000. * units.mbar, mixing)
print(e)
Out:
15.823863685716976 millibar
Take the odd units and force them to millibars
Out:
15.823863685716976 millibar
Take the raw vapor pressure and throw into the dewpoint function
td = mpcalc.dewpoint(e)
print(td)
Out:
13.854699858753747 degree_Celsius
Which can of course be converted to Fahrenheit
print(td.to('degF'))
Out:
56.93845974575668 degree_Fahrenheit
Now do the same thing for 850 mb, approximately the pressure of Denver
e = mpcalc.vapor_pressure(850. * units.mbar, mixing)
print(e.to(units.mbar))
Out:
13.450284132859428 millibar
And print the corresponding dewpoint
td = mpcalc.dewpoint(e)
print(td, td.to('degF'))
Out:
11.3770989195134 degree_Celsius 52.47877805512405 degree_Fahrenheit
Total running time of the script: ( 0 minutes 0.005 seconds)