Why Storm Ophelia turned the sky orange across London and UK

1/22
Francesca Gillett16 October 2017

The sky over England appeared to glow orange and yellow today in a strange phenomenon caused by Storm Ophelia.

Stunning images of the so-called "red sun" were shared by people across the country as they compared the weather to looking through tinted glasses.

According to experts at the Met Office, the rare spectacle was caused by Storm Ophelia pushing warm air from Africa northwards, and with it came Saharan dust.

The dust brought a yellowish haze over the city.
John Manthorpe

As the air moved north towards Ireland and the UK, it gathered smoke and tiny debris from recent wildfires in Spain and Portugal.

Why does dust affect the colour of the sky?

When there are dust particles in the air, these obstruct the path of incoming sunlight. Light which is shorter in wavelength, like blue and violet, are unable to penetrate through the atmosphere, so are scattered away.

But light of longer wavelengths, including yellow, orange and red light, is still able to get through – thus giving the warm tint as seen today.

London was shrouded in orange on Monday.
BellaAMorley

The fascinating explanation also accounts for why sunrises and sunsets are often red and orange: when the sun is lower in the sky, the light has to pass through more particles in the atmosphere.

Red sunsets are often observed best from a beach, because of the salt particles suspended in the air above the sea.

The phenomena was caused by Ophelia pulling dust over from southern Europe and Africa.
PetalsofPerfection (Twitter)

For the majority of people the dust is not thought to pose a health risk, but sufferers of severe asthma are being urged to stay indoors where possible.

Sonia Munde, head of the helpline at Asthma UK, said: "We are deeply concerned about the toxic air from Saharan dust that Hurricane Ophelia has churned up, as this could pose a severe risk for the 5.4 million people in the UK who have asthma.

"Winds picking up dust and particles in the air could trigger potentially fatal asthma attacks."

Today's movement of air up from the continent saw temperatures rise, with highs of 22C in parts of southern England today, including London.

Ophelia, which had been speeding over the Atlantic as a category three hurricane before being downgraded to a post-tropical storm, hit the south west tip of Ireland on Monday morning.

On Monday evening, the storm arrived in west Wales and Northern Ireland, where tens of thousands of homes are without power.

Create a FREE account to continue reading

eros

Registration is a free and easy way to support our journalism.

Join our community where you can: comment on stories; sign up to newsletters; enter competitions and access content on our app.

Your email address

Must be at least 6 characters, include an upper and lower case character and a number

You must be at least 18 years old to create an account

* Required fields

Already have an account? SIGN IN

By clicking Create Account you confirm that your data has been entered correctly and you have read and agree to our Terms of use , Cookie policy and Privacy policy .

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged in