The amount of light that has been filtered by water and is entering the atmosphere affects how red a sunset is. This is one of the reasons a horizon that is more than a mile away from the sun appears to turn red. There’s also a geographic factor, with many locations where a sunset is red being over water and those with very long distances of land being over areas of forest.
Though one might think the higher the atmospheric level, the longer the sunset, that’s not the case. One of the beautiful things about sunset, and it’s also a pain because you have to wait so long for it, is that we have this concept of water separating the light into colors. As the water gets lower, it gets less reflective and there’s more color.
Sunset in Saint-Malo
Summer sunsets are short but vibrant, thanks to the location’s elevated latitude and the amount of sunlight that filters in during the day, making for a rich spectrum of color. But it’s not just how much light reaches the ground that determines a sunset’s quality. The color of the light that does reach the ground affects how the sun sets. This is also known as the “sky color” effect.
With each layer of Earth’s atmosphere making up a color spectrum, the sunlight that reaches the Earth determines what that layer of color looks like.