Monday, June 09, 2008

African dust over Europe

In the last days of May there was an expansive dust layer above central Europe that caused a lot of interesting atmospheric phenomena. The story begun on 27th of May, when an ochre colored aureole surrounded the sun, and the sunset was pale yellow what repeated the next morning. There was a 7-8 degrees wide, dark greyish band by the horizon (image by Ágnes Kiricsi, in Vecsés, Hungary) this made the dawn to be late and the sunset to be too early. On the next days Bishop’s ring was observed through Central Europe – in the Czech Republic, in certain parts of Germany, and in Hungary. (This Bishop’s ring looks the same as it was produced by volcanic particles.)

In the Alps the dust strongly reduced the transparency of air (to about 3-4 kms).
The photo was taken by Bertram Radelow in Davos, Switzerland. The situaution was the same in the northern and eastern parts of the Alps.










The last two days of May passed away with the attenuation of the dust layer, dust fell out – both dry and wet way. At my hometown the dry version occured and a thin layer of fine yellowish powder subsided on the plants and the parking cars. In Germany there was a reddish-ochre coloured muddy rain falling that caught attention. The same thing happened at some places in Hungary too where rainshowers washed out the dust leaving muddy traces on everything.



In the meanwhile the dust „cloud” could even reach southern Scandinavia, where it also produced „colorless” sunset. The photo was taken by Andras Uhrin in Stavanger, Norway.










The origin of the dust is in the deserts of Africa. Late spring and early summer there are proper conditions in the Sahara and Sahel region for the fine dust to lift up high in the atmosphere where hot, dry winds transport it towards Central Europe, causing the same phenomena almost each year. There were „blood rains” in Europe caused by this Saharan dust over the centuries, like the ’Blutregen’ in 1901 in Germany, when the dust mass that fell out was 1-4 grams / square meter! The micron sized particles are mixed of fine sand and fine mica pellets.