3.8.5

Correct 'Shade' temps for night

assets/js/physics.js

@@ -14,6 +14,7 @@
 //    calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType, ventilated, speedMph, windMps)  equilibrium cabin temp
 //    calcVehicleInteriorTempPass(TaArr, globArr, elevArr, vaArr, vehicleType, ventilated, speedMph)  lagged cabin temp
 //    calcShadeAirTemp(TaEnv, effRadEnv, va, elev, shade)  per-env shade air temp
+//    calcShadeFeltTemp(TaShade, difEnv, va, eh, elev, shade)  felt temp in that shade
 //    vaporPressureHpa(Ta, RH)              Magnus formula - hPa
 //    solarElevationDeg(lat, lon, dateUTC)  NOAA simplified solar position (-)
 //    calcTmrt(Ta, dirRad, diffRad, globalRad, solElev)  Mean radiant temperature
@@ -601,9 +602,55 @@ export function calcShadeAirTemp(Ta, effectiveRad, va, elev, shade) {
   const daytime = (elev != null && elev > 0) ? 1 : 0;
   const sunTerm  = SHADE_K_SUN  * (shade.sun ?? 0)        * rad * daytime;
   const windTerm = SHADE_K_WIND * (1 - (shade.shelter ?? 0)) * Math.max(0, va || 0);
-  const adj = sunTerm - windTerm;
+  // Wind can only cancel the sun-trap warming, never push the pocket BELOW
+  // ambient: mixing drags trapped air back toward the open-air reading, it
+  // does not manufacture cold. Without the floor a breezy night read a
+  // degree under Air for no physical reason (and Pet Shade with it).
+  // Genuinely cool environments still sit below Air via env.taOffset.
+  const adj = Math.max(0, sunTerm - windTerm);
   // Local sun-trap nudge only - the env air-temp shift is already in Ta.
-  return Ta + Math.max(-4, Math.min(5, adj));
+  return Ta + Math.min(5, adj);
+}
+
+// -------------------------------------------------------------------
+// SHADE FELT TEMPERATURE - "SunSoak, but out of the sun"
+// -------------------------------------------------------------------
+// calcShadeAirTemp() above answers "what would a thermometer in the shade
+// read". That is NOT what someone standing in the shade feels: they are
+// still outdoors, so wind still strips heat off them and humidity still
+// blunts their sweating, exactly as in the open. Reading a shade AIR temp
+// beside SunSoak's FELT temp made Shade look hotter than full sun on a
+// breezy night - both numbers were right, but they were different
+// quantities sitting in adjacent columns.
+//
+// So Shade runs the same UTCI machinery as SunSoak, changing one input:
+// the radiant load. Out of the beam a person sees no direct sun, only the
+// part of the sky their shade does not block, so:
+//
+//   direct     -> 0            (that is what shade IS)
+//   diffuse    -> difEnv * skyView
+//   global     -> the same diffuse (no beam reaching the ground to reflect)
+//
+// skyView derives from shade.shelter, reusing it as an enclosure proxy: a
+// forest canopy or building canyon that stops the wind also hides most of
+// the sky dome, while an umbrella on open sand blocks little besides the
+// sun itself. It is a proxy, not a measurement - like the rest of the
+// shade block, this is an estimate of a typical spot in that environment.
+//
+// Consequences worth knowing: at night there is no beam to remove, so
+// Shade converges on SunSoak (they differ only by the sun-trap nudge in
+// the air temp). In daytime sun Shade sits several degrees under SunSoak,
+// which is the whole point of standing in it. On a windy hour BOTH fall
+// together, because both now carry the same wind term.
+// -------------------------------------------------------------------
+export const SHADE_SKY_BLOCK = 0.6;  // fraction of the sky an enclosed shade hides, per unit shelter
+
+export function calcShadeFeltTemp(TaShade, difRad, va, eh, elev, shade) {
+  if (TaShade == null) return null;
+  const skyView  = 1 - SHADE_SKY_BLOCK * (shade?.shelter ?? 0);
+  const difShade = Math.max(0, (difRad || 0) * skyView);
+  const Tmrt = calcTmrt(TaShade, 0, difShade, difShade, elev);
+  return utciApprox(TaShade, Tmrt, va, eh);
 }
 
 // -- Pets Profile - Fur Surface Temperature -----------------------------------