A bright, almost artificial band of orange over a flat ocean is not a sign of pristine air. It is often the signature of extra particles. Near the horizon, the sunlight plows through a much longer path of atmosphere stuffed with aerosols, salt, dust and pollution.
What looks romantic is, in part, a filter. Shorter blue and violet wavelengths are stripped out by Rayleigh scattering along that long slant path, while larger particles trigger Mie scattering that redirects reds and oranges toward your eye instead of letting them pass into space. The calm ocean helps twice: it suppresses whitecaps that would break up the reflection, and it acts as a dark, smooth mirror that boosts the apparent saturation of whatever color survives the trip through the haze.
So the sky can look more vivid not despite the dirty air, but because of it. Extra fine particles increase optical depth, deepen the contrast between glowing horizon and dimmer upper sky, and carve out that sharp line of fire you photograph and then quietly forget came from pollution.
