# 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:

```15823.863685716977 gram * millibar / kilogram
```

Take the odd units and force them to millibars

```print(e.to(units.mbar))
```

Out:

```15.823863685716978 millibar
```

Take the raw vapor pressure and throw into the dewpoint function

```td = mpcalc.dewpoint(e)
print(td)
```

Out:

```13.854699858753728 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:

```13.45028413285943 millibar
```

And print the corresponding dewpoint

```td = mpcalc.dewpoint(e)
print(td, td.to('degF'))
```

Out:

```11.377098919513376 degree_Celsius 52.47877805512405 degree_Fahrenheit
```

Total running time of the script: ( 0 minutes 0.006 seconds)

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