The unusual colour of the sky and the redness of the sun today is likely to be due to smoke from wildfires occurring over northern Iberia along with desert dust high up in the atmosphere originating from North Africa. Some aircraft flying at altitude have reported a smell of burning in the cabin which reinforces this theory.
As ex hurricane Ophelia passes to the west of the UK is it bringing with it air from much further south and this air is not only giving us today’s muggy weather but also bring dust with it. This dust scatters the blue light from the sun letting more red light through much as at sunrise or sunset.
However, measurements from the surface air quality network show no evidence of significant dust concentrations in the air at the surface.