tephpy.plotting.shading#

CAPE/CIN shading geometry for the tephigram (spec §3.2).

Free builders in the isopleths pattern: pure functions over bare numpy arrays in diagram-native units (hPa, °C — the spec §5 exemption) that return closed polygons in (temperature, theta) space, headlessly testable. TephigramAxes.shade_cape/shade_cin draw them through the tephigram transform as one compound-path PathPatch per call.

Both curves are sampled onto their merged pressure grid along the drawn polylines — the straight segments in tephigram (x, y) space that matplotlib draws between profile levels — with a vertex inserted at each exact segment intersection, so the fill closes on the plotted lines at every scale (any other interpolation bows away from the drawn chords between levels). The regions are bounded as metpy.calc.cape_cin() integrates (its which_lfc="bottom"/which_el="top" defaults): CAPE is the positive-buoyancy region between the LFC — the bottom of the lowest positive run at or above the LCL — and the EL — the top of the highest such run, which is the profile top while the parcel is still buoyant there; CIN is the negative-buoyancy region between the parcel start and the LFC. With no LFC there is neither region (cape_cin returns 0 J/kg for both). Two documented divergences from the numbers: cape_cin finds its bounds on virtual-temperature profiles and integrates the net virtual-temperature difference (Doswell & Rasmussen 1994), neither of which the plotted temperature curves can show — the shading is the drawn-curve region between the same rules’ bounds, and the annotated J/kg number remains the quantitative truth.

Functions#

`cape_polygons`(→ list[numpy.typing.NDArray[numpy.float64]])	Build the CAPE region's closed polygons (spec §3.2).
`cin_polygons`(→ list[numpy.typing.NDArray[numpy.float64]])	Build the CIN region's closed polygons (spec §3.2).

Module Contents#

tephpy.plotting.shading.cape_polygons(pressure: numpy.typing.ArrayLike, temperature: numpy.typing.ArrayLike, parcel_pressure: numpy.typing.ArrayLike, parcel_temperature: numpy.typing.ArrayLike, *, lcl_pressure: float) → list[numpy.typing.NDArray[numpy.float64]][source]#

Build the CAPE region’s closed polygons (spec §3.2).

Parameters:

pressureArrayLike: Environment pressures in hPa, strictly decreasing.
temperatureArrayLike: Environment temperatures in degrees Celsius; NaN gaps break the region.
parcel_pressureArrayLike: Parcel-path pressures in hPa, strictly decreasing.
parcel_temperatureArrayLike: Parcel-path temperatures in degrees Celsius.
lcl_pressurefloat: Pressure of the LCL the parcel uses, in hPa; buoyancy below it never counts towards CAPE.

Returns:

list of numpy.ndarray: One (N, 2) closed polygon in (temperature, theta) space per uninterrupted positive-buoyancy run — plural when the region is interrupted, empty when there is no CAPE (0 is an answer, not an error; spec §6).

tephpy.plotting.shading.cin_polygons(pressure: numpy.typing.ArrayLike, temperature: numpy.typing.ArrayLike, parcel_pressure: numpy.typing.ArrayLike, parcel_temperature: numpy.typing.ArrayLike, *, lcl_pressure: float) → list[numpy.typing.NDArray[numpy.float64]][source]#

Build the CIN region’s closed polygons (spec §3.2).

Parameters:

pressureArrayLike: Environment pressures in hPa, strictly decreasing.
temperatureArrayLike: Environment temperatures in degrees Celsius; NaN gaps break the region.
parcel_pressureArrayLike: Parcel-path pressures in hPa, strictly decreasing.
parcel_temperatureArrayLike: Parcel-path temperatures in degrees Celsius.
lcl_pressurefloat: Pressure of the LCL the parcel uses, in hPa; it locates the LFC that bounds the region.

Returns:

list of numpy.ndarray: One (N, 2) closed polygon in (temperature, theta) space per uninterrupted negative-buoyancy run between the parcel start and the LFC — empty when there is no LFC (cape_cin reports both CAPE and CIN as zero then) or no inhibition below it.