Storm in Sahara sends dust to UK

31 03 2014

Red dust covering cars in the south this weekend was blown in from the Sahara Desert.  A large amount of sand and dust was swept up by storm winds in the desert, around 2000 miles away in northwest Africa. The airborne particles were blown north to the UK where they combined with our warm air and were deposited during showers.

Paul Hutcheon at the Met Office said “We usually see this happen several times a year when big dust storms in the Sahara coincide with southerly winds to bring that dust here. More dust rain is possible during showers expected later this week.”

Saharan dust is lifted by strong winds and can reach very high altitudes; from there it can be transported worldwide by winds, covering distances of thousands of kilometers. The dust gets caught in rain droplets in clouds, falling to the ground in rain. When the water evaporates, a thin layer of dust is left on surfaces, like cars. It can also lead to vivid sunsets.

Generally winds of more than 20 miles per hour are needed to lift sand at the Saharan Desert has been experiencing some gale force winds (over 40 miles per hour).

Saharan dust is also a contributing factor to air quality in addition to pollution levels and weather conditions.

 

Sahara-dust-update

The dust, shown in pink within the red circle, is carried within clouds, shown in red, to the UK, where it falls within rain showers.





Dust storm brings Saharan sand to the UK

28 06 2012

Many people across parts of the UK have noticed a layer of light dust on their cars or other surfaces over the past couple of days, but how did it get here?

A big dust storm in the Sahara, around 2,000 miles away, is to blame.

Late last week the storm swept up a large amount of sand and dust from the western Sahara up into the atmosphere.

It then spread westwards out over the Atlantic before getting caught up in southerly winds, dragging it north over Spain before it arrived over the UK mixed up in the warm and humid air which has brought thunder storms and heavy rain to the country.

The dust can get caught up in the rain droplets in clouds, which then fall to the ground. When the water evaporates, a thin layer of dust is left on surfaces, like cars.

Many people noticed this in the South West of the UK yesterday, with the dust then spreading north and east overnight to bring it to a much wider area.

Paul Hutcheon, Deputy Chief Forecaster at the Met Office, said: “We usually see this happen several times a year, particularly in summer when you get these big dust storms in the western Sahara and the southerly winds to bring that dust here.

“This event was a very well-marked example, as you can clearly see the dust as it moves from the Sahara to the UK in the satellite imagery.”

The satellite animation above shows the dust as a bright pink blob over Africa at the start of the sequence, which then moves north over to the UK – initially arriving over the South West, but then moving north and east. You can clearly see the dust-laden airmass of warm and humid air, with a marked boundary to the clear air from a cold front to the west.





Saharan dust heads for the UK

8 04 2011

A wind storm that developed over northwestern Africa on the 3rd and  4th April left a legacy of Saharan dust in the atmosphere over parts of Western Europe.

Gusty winds reached 50mph at times over southern Morocco and western Algeria on Sunday and Monday, with the shifting sands of the Sahara thrown into the atmosphere as the sandstorms affected much of the region.

By midweek, the low pressure system that brought poor visibility to parts of Saharan Africa moved away south and weakened – but only after sand particles had been lifted into the air.

South easterly winds over the Sahara took the air borne sand particles eastwards and off the Atlantic coast of Africa. Once here, the Saharan dust was eventually blown by south westerly winds that often cross the Atlantic Ocean and towards the UK.

With conditions over the UK mainly settled thanks to high pressure over the country, dust carried from distant southern shores is stalling over the southwestern approaches of the British Isles at a height of between five and ten thousand feet.

The satellite animation above shows the dust as a bright pink blog over Africa at the start of the sequence, which then moves north to the west of Portugal.  At the end of the sequence the dust stretches from Biscay to Brittany and into some western parts of the UK, with the highest concentrations passing over Cornwall. This is expected to give vivid sunsets here for a time until the dust disperses over the coming days.

Satellite image showing the Saharan dust to the south west of the the UK at 1100 GMT on Friday 8th April (source: Dundee SatelliteReceiving Station)








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