clouds: remove terrain-height march breaks causing holes

config.js

@@ -144,7 +144,7 @@ window.CONFIG = {
     // altitude so aircraft fly above the deck.
     clouds: {
         top: 1.0,                 // ~12.9 km
-        bottom: 0.0,              // deck base at the terrain datum
+        bottom: -0.2,             // ~-2.6 km (deck base slightly below terrain)
         // Coverage per weather level, 0 = clear, 1 = overcast. Only the
         // levels listed here override the built-in defaults
         // (sunny 0.20, cloudy 0.70, stormy 0.80, night 0.45). Live weather

vendor/clouds3d.js

@@ -501,7 +501,6 @@ var FRAG_SRC = [
             'p.y += (ign(gl_FragCoord.xy + vec2(float(i) * 7.13, float(i) * 3.71)) - 0.5) * stepSize;',
             'float py = p.y + earthDrop(p.xz);',
             'if (py > uCloudTop || py < uCloudBot - 0.1) break;',
-            'if (uElevOn > 0.5 && py < terrElev(p.xz) * uElevScale) break;',
             'if (tTerrain > 0.0 && t >= tTerrain) break;',
             'float cSoft = smoothstep(7.0, 20.0, t);',
             'float d = cloudDensity(p, baseThresh, cSoft);',