London, March 26 (IANS): Imagine colours of a painting that can tell the environment information in earth's past atmosphere in places centuries ago when instrumental measurements were not available?

A team of Greek and German researchers has shown that the colours of sunsets painted by famous artists can be used to estimate pollution levels in the earth’s past atmosphere.

These paintings reveal that ash and gas released during major volcanic eruptions scatter the different colours of sunlight, making sunsets appear more red.

When the Tambora volcano in Indonesia erupted in 1815, painters in Europe could see the colours of the sky changing.

The volcanic ash and gas spewed into the atmosphere travelled the world and, as these aerosol particles scattered sunlight, they produced bright red and orange sunsets in Europe for up to three years after the eruption.

“JMW Turner was one of the artists who painted the stunning sunsets during that time.
Now, scientists are using his, and other great masters’ paintings to retrieve information on the composition of the past atmosphere,” explained Christos Zerefos, a professor of atmospheric physics at Academy of Athens in Greece.

We found that colouring sunsets is the way their brains perceive greens and reds that contains important environmental information, he added.

Zerefos and his team analysed hundreds of high-quality digital photographs of sunset paintings done between 1,500 and 2,000, a period including over 50 large volcanic eruptions around the globe.

They were looking to find out whether the relative amounts of red and green along the horizon of each painting could provide information on the amount of aerosols in the atmosphere.

“We found that red-to-green ratios measured in the sunsets of paintings by great masters correlate well with the amount of volcanic aerosols in the atmosphere regardless of the painters and of the school of painting,” Zerefos noted.

Skies more polluted by volcanic ash scatter sunlight more, so they appear more red. Similar effects are seen with mineral (desert dust) or man-made aerosols.

Air with a higher amount of aerosols has a higher ‘aerosol optical depth’, a parameter the team calculated using the red-to-green ratios in the paintings.

The results were published in Atmospheric Chemistry and Physics, an open access journal of the European Geosciences Union (EGU).