It’s been two months since many people in Kent were left confused after waking up to orange skies and finding smears on their vehicles. Saharan dust, also known as “blood rain”, is expected to return to the country later this week.
These downpours are triggered by fine dust from the Sahara which can turn the rain a brownish red, hence its name. It can leave vehicles covered in dust or even streaked with reddish rain.
The vast cloud of airborne dust had its movements predicted by aerosol forecasts from the Copernicus Atmosphere Monitoring Service (CAMS). While part of the cloud looks set to head west over the Atlantic Ocean, another plume is expected to arrive in the southeast of the country in the coming days.
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CAMS atmospheric physicist Mark Parrington told MailOnline that ‘most dust transport is likely to be at higher altitudes, which could lead to hazy skies, rather than impacts on surface air quality”. as reported by the Express. “It may also be mixed with rain, which is also forecast for Friday, so there could be surface deposits on the cars after the rain clears.”
The Sahara is the main source of so-called “mineral dust” – amounting to some 60 to 200 million tonnes each year – blown from the surface of the desert. Convection currents over the Sahara are capable of lifting this airborne material to high altitudes, from where it can be carried thousands of kilometers by winds.
These plumes are known to play an important role in mediating tropical weather patterns, as the presence of dust can hamper the development of hurricanes. Saharan plumes typically reach the UK several times a year, when large dust storms over the vast desert coincide with southerly winds.
As the Met Office explains: “To get dust down from the sky to the ground, you need something to wash it from the sky: rain. When raindrops fall, they accumulate dust particles on their way down.
“Then when raindrops land on something and eventually evaporate, they leave behind a layer of dust.” The phenomenon – known as ‘blood rain’ – is largely harmless, although the presence of dust plumes in the air is known to affect air pollution levels and can worsen respiratory problems .
Southern parts of the UK were last hit by a Saharan dust cloud in March, leaving some areas covered in a light layer of fine red material. The same plume also caused record concentrations of peat dust in southern Spain, where skies appeared to turn orange as a result.
According to scientists, this cloud eventually reached as far north as Scandinavia.
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