Saharan dust falls across the UK
Saharan dust? Here in the UK? Really? Well, if you see a thin layer of dust on your car in the coming days, that is what it could be.
Since yesterday, lots of people have been sending me pictures on Twitter of their cars covered in dust. I noticed it too, on my journey to work this morning.
Whilst it doesn’t happen often, when it does, it is very noticeable – especially if you’ve just washed your car and it suddenly gets dirty again.
In order to work out how the dust got here, you need to take a look back at what the wind in the upper part of the atmosphere has been doing in recent days.
Sure enough, this weekend, the wind in the upper of the atmosphere over the UK was blowing in a southerly direction – all the way from north Africa and the Sahara Desert.
The image below from EUMETSAT, taken at around midday on Sunday, is an atmospheric motion vectors (AMV) product. It shows wind vectors at different heights derived by tracking the motion of the clouds and other atmospheric constituents.
It shows that the wind in the upper part of the atmosphere (pink and red wind barbs) over the UK was blowing from southerly direction – all the way from north Africa and the Sahara desert.
How does the dust get into the sky?
Just as in other parts of the world, the wind can blow strongly over deserts too – whipping up dust and sand high into the sky.
The wind in upper part of the atmosphere then transports the dust in the direction in which it’s travelling.
So, as this wind was blowing towards us at the weekend, it brought the dust with it.
How does the dust get down to the ground?
In order for the dust to get from up in the sky down to the ground, you need something to wash it out of the sky, and that something, is rain.
When the raindrops fall, they collect particles of dust on the way down. Then when the raindrops land on something and eventually evaporate, they leave behind a layer of dust.
So, if you spot a layer of dust on your car, have a think at just how far it’s travelled to get here!
If you take any pictures of Saharan dust, send them to me on Twitter – @liamdutton
— Jac Osborne (@JacOsborne15) March 31, 2014
— Beata Milne (@Beataher) March 31, 2014