A plume of dust may arrive in the UK this week, leading to dramatic sunrises and sunsets, as well as possible blood rain.
The fine particles of dust and sand have been carried on the wind for thousands of miles, all the way from the Sahara Desert, in north Africa.
The Met Office told BBC Science Focus: “The airborne dust is expected to continue moving across the UK through today and tomorrow. This can lead to hazier skies and, at times, deposits of dust on surfaces, such as cars, particularly if showers occur.”
During sunrise and sunset, the dust may transform the sky into deep golden and orange hues.
“Dust particles scatter light from the sun very effectively, helping to cause red sunsets,” said Dr Claire Ryder, associate professor in mineral dust processes at the University of Reading.
“Iron oxides in dust also absorb blue colours in sunlight, further enhancing red colours.”
Those iron oxides could even cause blood rain – a sight that’s not quite as dramatic as it sounds.
“Despite the dramatic name, it’s a straightforward phenomenon,” explained Ryder. “As rain falls through air thick with Saharan dust, it picks up tiny particles of reddish-brown sand, leaving rusty orange smears on cars, windows and garden furniture.
“If your car looks like it’s been lightly coated in mud after a shower this week, this is why.”
The rain that’s been forecast in England on Friday could, therefore, be blood rain – but the Met Office said it was unlikely to appear bright red.
Dust-laden rain in the UK is usually at such low concentrations that droplets appear normal to the naked eye.
But you may wish to postpone your car wash until the end of the week, so you don’t have to do the job twice.
Aside from just your car, this Saharan dust may affect air quality, increasing the concentrations of particulate matter – that is, pollution – in the air.
This may be made worse by the pleasant springtime weather. With only light winds in the south and east of the UK, the dust could linger and build up in certain regions.
However, the Met Office said that there was no need for concern from a health perspective. At most, individuals with pre-existing respiratory conditions may notice a very slight worsening of air quality.
Saharan dust may seem like an unlikely addition to UK air, but it’s actually not unusual. Sand gets transported northwards when dust storms in the north African desert interact with certain wind patterns.
“Over the coming days, southerly winds ahead of an approaching weather front will push the plume across the UK, and forecasts suggest the dust could linger until late on Sunday,” said Ryder.
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