Two changes that bring /skewt visually and analytically into parity
with the NOAA SPC sounding viewer
(https://www.spc.noaa.gov/exper/soundings/):
NOAA-style line set
-------------------
Updated the SkewtSvg style block to match the public SPC chart:
* Temperature trace ........ pure red (#ff0000) at 2.5 px stroke
* Dewpoint trace ........... pure green (#00aa00) at 2.5 px stroke
* Isotherms ................ dashed teal (#14b8a6)
* Dry adiabats ............. solid orange (#f59e0b)
* Moist (saturated) adiabats dashed sky-blue (#38bdf8)
* Mixing-ratio lines ....... dotted darker green (#16a34a), with
labels at 700 mb showing the g/kg
value, drawn only below 600 mb (matches
the SPC chart's lower-band number row)
* Parcel ascent ............ new dashed grey (#475569) line, drawn
whenever SkewtParams.derive returns a
non-empty parcel_trace
The mixing-ratio set is the SPC standard (0.4 / 0.7 / 1 / 2 / 3 / 5 /
8 / 12 / 16 / 20 g/kg) instead of the prior arbitrary set.
SkewtParams: SPC parcel-theory + indices module
-----------------------------------------------
New `Microwaveprop.Weather.SkewtParams` derives the parameter set that
ships in the SPC `*.txt` companion file:
* LCL pressure / temperature / height (Bolton 1980 eq 22)
* LFC pressure / height
* EL pressure / height
* SBCAPE, SBCIN (J/kg, virtual-temperature integration with
surface parcel)
* 3 km CAPE
* Lifted Index (parcel ↔ environment T at 500 mb)
* Freezing level (T = 0 °C height) and Wet-Bulb Zero
* DCAPE (downdraft CAPE — picks the min-θₑ source level in
400–700 mb, descends moist-adiabatically to surface)
* Layer lapse rates: sfc–3 km, 700–500 mb, 850–500 mb
* `parcel_trace` — pressure/temperature trajectory used by
SkewtSvg to draw the dashed parcel-ascent overlay
Wind-derived indices (SRH, BWD, Bunkers motion, SCP, STP, SHIP) are
deliberately *not* produced and the LiveView surfaces a one-line note
explaining why: HRRR persists wind only at 10 m AGL, so per-pressure-
level shear can't be computed from this data source.
LiveView panel restructured into grouped sections (Surface, Convective
parcel, Levels, Lapse rates, Moisture/stability, Refractivity) so the
layout matches the SPC viewer's order. The Levels rows show pressure
*and* height ("872 mb · 1,140 m") for quick cross-reference between
the diagram axis and the readout.
Tests: 8/8 new SkewtParamsTest cases (LCL Bolton check, saturated-air
edge case, full field-set presence, summer profile produces SBCAPE > 0
and LI < 0, capped profile produces SBCAPE = 0 and LI > 0, freezing
level interpolated correctly, sfc–3 km lapse rate, empty profile no
crash). 25/25 across all skewt-related test files. mix test green
(2,902 / 2,902 + 221 properties), mix credo --strict clean, mix
assets.build clean.
Graham McIntire
be1174914f