Red Sun Phenomenon Explained

Particles from the Sahara Desert, and Portugal wildfires fanned by hurricane Ophelia winds produced the spectacle.

Red sun in the morning sky over Helsinki on 17th October / Credit; @rockaroundtblog Instagram / Sami Ruokakangas

If you looked upwards in Finland on Tuesday you probably saw the sky and sun were distinctly more red than usual.

That’s because particles from wildfires in Portugal, and sand from the Sahara have been swept up into the air, to create the rosy filter.

It’s a phenomenon that we might see on Wednesday also.

“In parts of Europe, the sky will be red on Wednesday, but in Finland it’s not quite so certain” says Seppt Hassinen, Senior Scientist at the Finnish Meteorological Institute FMI.

According to Hassinen, satellite images showed the reddish cloud extended from the Netherlands, through Denmark and Sweden and over Finland – as far north as Jyväskylä.

The visuals were explained by the particulates in the air, but also by hurricane Ophelia.

“The hurricane winds caused a situation where dust and smoke were carried into Britain and Ireland, and then towards the direction of Finland” explains Hassinen.

Uncommon Sight

It’s fairly uncommon, says Hassinen, for dust from the Sahara to be pushed this far north into Finland in such quantities.

“Usually dust is only detected in laboratory tests. Very occasionally, dust will stain the surface of snow, but not even every year” he says.

Hassinen says the red colour is created when the dust particles scatter blue light wavelengths, but the long wave red light still comes through the clouds, so the blue light disappears, and on the planet’s surface, we only see the red colour.