IF YOU'RE in the eastern coastal provinces of Spain at the moment, you may have stepped outside on Saturday and found the landscape had turned orange – a film of clay-coloured dust that looked as though they'd been cutting terracotta tiles in heaven.
Desert sand on mountain snow in Benasque, Huesca province, Aragón (photo: AEMET on Twitter)
And even though it's messy, it's actually a good thing and helpful to the atmosphere, reveals the State meteorological agency, AEMET.
'Sahara rain' always creates extra work for Mediterranean residents, what with sweeping their terraces and cleaning their cars and windows, and according to head of Alicante University's Faculty of Climatology, Dr Jorge Olcina, the 'sandstorm' seen in the early hours of Saturday morning is the 'most intense' since June 2018.
It happens when an atmospheric front 'drags' sand floating above the surface from the Sahara desert, caught up by a south or south-westerly wind, and normally comes during unsettled conditions – not necessarily gales or storms as we know them, but in a typical 'heat-meets-cold' or 'humid-meets-polar' air clash.
Dr Olcina, who is also chairman of the Spanish Geographers' Association (AGE), says for the 'orange effect' to occur, the rain combined with the desert sand in suspension has to be very fine and very light – of the type where people barely notice it and hold out their hands to feel for drops, with a puzzled expression on their faces; even 'Scotch mist'-type rain would be too heavy for it to happen.
This is because the water needs to evaporate quickly to leave the solid residue, or sand, behind, if Mother Nature is aiming to create a 'Martian look'.
The sand then settles, coming down to earth and landing on every available surface – a good reason why, before leaving washing hanging out on the line overnight, you should check the wind direction just in case, especially if said washing is white.
But why is what they call 'blood rain' a positive phenomenon?
It's messy, but it's actually a good thing (photo: AEMET on Twitter)
“It reduces acidity in the atmosphere,” explains Dr Olcina.
“This improves air quality.”
Maybe not if you're outside when it happens, but once the dust settles, the air is apparently cleaner and healthier to breathe for a while, and pollution levels are reduced.
'Sahara rain' is most common on the Mediterranean seaboard, specifically on the coast, but up to two or three provinces inland, so the whole of mainland Spain's eastern strip and the Balearic Islands are likely to be affected to some degree or another.
In fact, the above photographs, by AEMET on Twitter, show the snow-covered Pyrénées in Benasque, Huesca province, northern Aragón – home to the Cerler ski resort – with an amber tinge, looking as though they had turned into a desert.
AEMET says 'sand rain' has been getting more and more frequent in this part of Spain since around the year 1990, which is, Dr Olcina argues, evidence that climate change really is real.
“It means there's a greater and greater presence of atmospheric flows coming up from northern Africa towards southern Europe and the Mediterranean basin,” he explains.
