In October 2017 across the UK we were treated to a Red Sun in a hazy dark sky. Some street lights even came on.
Air was pulled from southern Europe and Africa and that air contained a lot of dust. It was linked to hurricane Ophelia
The dust got picked up from the Sahara Desert into the air and went high up into the atmosphere, above the UK.
Because the dust was so high, light from the sun was scattered in the longer wavelengths, which is in the red part of the spectrum, so it appeared red to the eyes.
It was a really bizarre phenomena.