During my travels, I’ve seen some outstanding sunsets – each of them was different, special in a way, and has been captured in my memory ever since. Going through my pictures, I started wondering – What makes Phuket have those beautiful sunsets? And why is Africa supposed to have the best ones Worldwide? In fact, what makes the color of a sunset?
Sunlight is composed of a spectrum of colors that range from blue/violet to orange/red. Each of the colors have a different wavelength – I don’t want to get too geeky, it’s probably easier if you picture a rainbow. The inner colours of the rainbow are violet and blue (which have the shortest wavelength); while the outer ones are orange and red, the colours with the longest wavelength.
At noon, the sun appears to be white because all wavelengths of visual light reach our eyes with almost the same intensity (remember that Pink Floyd album cover -The Dark Side of the Moon? That’s what I mean!). However, at sunrise and sunset, sunlight takes a much longer path through the atmosphere. Because air molecules scatter away the shortest wavelengths of light, the light that reaches our eyes is rather orange / red.
All good – But what makes sunsets in some parts of the World more beautiful than in others?
What determines actually the kind of sunset is the size and concentration of atmospheric particles in the path of the incoming sunlight. Very small particles scatter blue and violet light preferentially, leading to a glowing orange and red sunset. A heavy concentration of small particles will create even redder sunsets.
Does that mean that if we’re somewhere with high air pollution, we’ll get to see a better sunset?
No. Pollution particles are too large, so instead of enhancing the colors of the sky, they subdue them. This is also the reason for which sunsets in deserts and the tropics are more dramatic – the air pollution is rather minimal or non-existent!
Taking away pollution, there are many other smaller particles that can be floating in the air to create the perfect glowing reddish sunset, such as salt particles over the ocean, or dust and ash from a volcanic eruption.