Soundings and hodographs¶

fastplot.skewt has MetPy's SkewT and Hodograph classes, with the same methods and arguments, plus the few thermodynamic functions needed to draw the background lines and a parcel. pint quantities are accepted wherever MetPy accepts them.

import fastplot.pyplot as plt
from fastplot.skewt import SkewT

fig = plt.figure(figsize=(7, 7))
skew = SkewT(fig, rotation=45)
skew.plot(p, T, 'r')
skew.plot(p, Td, 'g')
skew.plot_barbs(p, u, v)
skew.plot_dry_adiabats()
skew.plot_moist_adiabats()
skew.plot_mixing_lines()
skew.ax.set_xlim(-30, 40)
fig.savefig('skewt.png')

A complete example, with a parcel, shaded CAPE and CIN and a hodograph inset, is in the gallery.

SkewT¶

Method	What it does
`plot(p, t, ...)`	A temperature profile, any matplotlib line style
`plot_barbs(p, u, v)`	Wind barbs down the right-hand side
`plot_dry_adiabats()`	Dry adiabats
`plot_moist_adiabats()`	Moist (pseudo-) adiabats
`plot_mixing_lines()`	Lines of constant mixing ratio
`shade_cape(p, t, parcel)`	Red where the parcel is warmer than the air around it
`shade_cin(p, t, parcel, dewpoint)`	Blue where it is colder, below the level of free convection
`shade_area(y, x1, x2, which)`	Any shading between two profiles

SkewT(fig, rotation=45, rect=(left, bottom, width, height)) places the diagram anywhere in a figure, leaving room for a hodograph or text. skew.ax is an ordinary axes for titles, limits and labels.

Hodograph¶

from fastplot.skewt import Hodograph

ax = fig.add_axes((0.7, 0.55, 0.25, 0.3))
hodo = Hodograph(ax, component_range=80)
hodo.add_grid(increment=20)
hodo.plot_colormapped(u, v, p, cmap='plasma_r')

plot, plot_colormapped (through a colormap, or a colour per interval of height) and wind_vectors match MetPy's.

Thermodynamics¶

Function	Returns
`dry_lapse(p, t0, p0)`	Temperature (K) of air lifted dry-adiabatically
`moist_lapse(p, t0, p0)`	Temperature (K) along moist adiabats
`saturation_vapor_pressure(t)`	hPa, over liquid water
`saturation_mixing_ratio(p, t)`	kg/kg
`dewpoint_from_vapor_pressure(e)`	°C

The moist adiabats integrate the same equation MetPy 1.7 does and agree with it to within 0.001 K.