Extraordinary sights of the sky were painted in vivid colours of yellow, orange, pink and red hues covering Europe and the UK this week! What is it? Where did it come from? What does it mean for our current climate? Professor Richard Washington teaches Climate Science at the University of Oxford and is Head of Extreme E’s Scientific Committee explains.

Extreme E: Why are we seeing such yellow and orange clouding our skies over Europe and the UK?
Professor Richard Washington: The colours we have seen reigning over our skies has been caused by Sahara Dust blowing in from a storm across the Mediterranean Sea, composed of a mix of both sand and dust by strong winds from the Sahara Desert, located in North Africa.

XE: The biggest question remains; how does this dust affect our planet and current climate?
RW: Dust is an important part of the earth system, including climate. During the day, the sun reflects off the dust and cools the atmosphere whilst during the night, it tends to warm the atmosphere. However, dust can also work like a greenhouse gas by absorbing heat radiated from the earth, causing warming. Exactly whether the overall effect is one of warming or cooling depends on all sorts of things like the size of the dust particle, the height of the dust and its size, shape and colour.

Dust also influences clouds and can affect the development of weather systems like tropical cyclones. The components of dust also fertilise the oceans and land areas like the Amazon Forest. This usually occurs during the winter where dust from the Bodele in Chad – where I was fortunate to take part in the first experiment to measure winds and dust in the world’s largest single dust source - crosses the Atlantic and is especially beneficial to the Amazon Forest as it lacks certain nutrients which the dust clouds help to facilitate, assisting the environment to thrive.

XE: How far it has travelled so far?
RW: The Sahara Dust storm has travelled over 3000km to the UK from the Sahara Desert where it originated in Algeria. As you can see from the Met Office below, the pink is the dust and the red is the deep clouds.

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