vertical_velocity_pressure#

metpy.calc.vertical_velocity_pressure(w, pressure, temperature, mixing_ratio=0)#

Calculate omega from w assuming hydrostatic conditions.

This function converts vertical velocity with respect to height \(\left(w = \frac{Dz}{Dt}\right)\) to that with respect to pressure \(\left(\omega = \frac{Dp}{Dt}\right)\) assuming hydrostatic conditions on the synoptic scale. By Equation 7.33 in [Hobbs2006],

\[\omega \simeq -\rho g w\]

Density (\(\rho\)) is calculated using the density() function, from the given pressure and temperature. If mixing_ratio is given, the virtual temperature correction is used, otherwise, dry air is assumed.

Parameters

w (pint.Quantity) – Vertical velocity in terms of height
pressure (pint.Quantity) – Total atmospheric pressure
temperature (pint.Quantity) – Air temperature
mixing_ratio (pint.Quantity, optional) – Mixing ratio of air

Returns

pint.Quantity – Vertical velocity in terms of pressure (in Pascals / second)

Examples

>>> from metpy.calc import vertical_velocity_pressure
>>> from metpy.units import units
>>> vertical_velocity_pressure(0.5 * units('cm/s'), 700 * units.hPa, 5 * units.degC)
<Quantity(-0.0429888572, 'pascal / second')>