miasma

The standing air of a plague district. Slow domain-warped fbm shaped into a band: thick and rolling along the bottom edge of the quad, thinning to nothing at the top, so a strip laid across the street reads as fog lying IN it rather than as a rectangle of haze.

The same shader draws the green miasma pooled in the street (art.weather.miasma_low), the pale fog that separates one parallax band from the next (art.weather.haze_far, art.weather.haze_band), and the smoke leaning off a chimney (art.weather.smoke).

fog_color.a is the whole strip's weight and is what the nine bells raise; top is how high the fog stands.