Deceptive and dangerous is the beauty of the intense pink-orange and red sunsets that close the short winter days.

If you often witness these visual ‘spectacles’ it may be that you live in a wretchedly polluted area like mine. 

You must think I’m obsessed if I even associate sunsets with my periodic returns on the subject. 

Actually, these sunsets conceal a massive presence of nitrogen dioxide in the atmosphere.

ISPRA Istituto Superiore per la Protezione e Ricerca Ambientale  explains nitrogen dioxide (NO2):
a reddish-brown gas, poorly soluble in water, toxic, with a strong, pungent odour and strong irritating power. It is a pollutant with a predominantly secondary component, as it is the product of the oxidation of nitrogen monoxide (NO).

Nitrogen dioxide is a widespread pollutant that has negative effects on human health and, together with nitrogen monoxide, contributes to photochemical smog.

Photochemical smog i.e. the formation of secondary pollutants is conditioned by the presence of light radiation in the ultraviolet region.

We grow up learning that the sky is blue, did you as a child ever have the ‘why?’ period?

Why the sky is blue is explained to us by Rayleigh’s Scattering. 

To summarise the concept in a small format, a bit like espresso 🙂 the scattering of light reflecting off small particles.

I would also point you to an interesting publication reporting on a study of sunsets in paintings, and at this point I cannot fail to mention William Turner. 

Title of the article published by EGU European Geoscinces Union:
Further evidence of the important environmental information content in the relationships between red and green depicted in the paintings of the great masters.

Assumption: We examine sunsets painted by famous artists as information for the optical depth of particles after large volcanic eruptions. Images derived from precision colour protocols applied to the paintings were compared with online images and found to provide accurate information.

We can imagine what changed in the atmosphere after volcanic eruptions, but there are no volcanoes here, so what happens?

When nitrogen dioxide particles are present in the air, it is as if a kind of geometry is created that obstructs the sun’s rays.

In these cases the red light through an interplay of different frequencies and wavelengths somehow manages to prevail.

Deceptive beauty.

That is why we see sunsets of intense, bewitching colours and allow ourselves to be enchanted by what is invisible to the eyes …