Clean boundary layer air behind a front allowed the vivid blue-red contrasts in this sunset to stand out sharply. Contrary to popular belief, pollution yields dimmer, blurrier and less colorful sunsets because of light blockage and diffusion by particle components of haze. So the optimal weather for good sunrise and sunset photos is when the boundary layer is at its cleanest. In this part of the country, that is often behind a strong cold front.
Norman OK (Jan 0) Looking WSW