# Hydrostatic Thickness#

Use functions from `metpy.calc` as well as pint’s unit support to perform calculations.

The code below uses example data from our test suite to calculate the hydrostatic thickness between the surface and 500-hPa level for the provided sounding data.

```import pandas as pd

from metpy.calc import (mixing_ratio_from_relative_humidity, relative_humidity_from_dewpoint,
thickness_hydrostatic)
from metpy.cbook import get_test_data
from metpy.units import units
```

Upper air data can be obtained using the siphon package, but for this example we will use some of MetPy’s sample data.

```# Set column names
col_names = ['pressure', 'height', 'temperature', 'dewpoint', 'direction', 'speed']

# Read in test data using col_names
skiprows=5, usecols=[0, 1, 2, 3, 6, 7], names=col_names)
```

Drop any rows with all NaN values for T, Td, winds

```df = df.dropna(subset=('temperature', 'dewpoint', 'direction', 'speed'
), how='all').reset_index(drop=True)
```

Isolate pressure, temperature, and dewpoint and add units

```p = df['pressure'].values * units.hPa
T = df['temperature'].values * units.degC
Td = df['dewpoint'].values * units.degC
```

Calculate the relative humidity to compute the mixing ratio

```rh = relative_humidity_from_dewpoint(T, Td)
mixrat = mixing_ratio_from_relative_humidity(p, T, rh)
```

Calculate the thickness from the pressure, temperature, and mixing ratio for the layer from the surface pressure to 500-hPa

```print(thickness_hydrostatic(p, T, mixing_ratio=mixrat, depth=p - 500 * units.hPa))
```
```5332.474521891769 meter
```

Total running time of the script: ( 0 minutes 0.015 seconds)

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