Study explains science behind one of the newest recognised clouds

May 10, 2017, University of Reading
Study explains science behind one of the newest recognised clouds
Asperitas cloud over Burnie, Tasmania. Credit: Gary McArthur

Citizen science has helped experts to explain how the newly-recognised 'wave-like' asperitas cloud is formed.

Scientists at the University of Reading combined , forecasts and laser cloud measurements taken at the time the rare cloud formations were reported by members of the public, to learn about the weather conditions that allow them to form.

Their findings, published in Royal Meteorological Society journal Weather today, show for the first time that asperitas is a low level cloud made of water – not ice as previously suggested - which develops its characteristic from atmospheric disturbances, such as weather fronts and storms.

Professor Giles Harrison, who led an international research team including scientists from the University of Reading's Meteorology department, the Met Office and the European Centre for Medium Range Weather Forecasting said: "The sky is often full of clues to weather changes, and asperitas provides distinctive visualisation of complex and turbulent air motions in the lower atmosphere."

"Reading the sky is a key part of meteorological education, warning aviators and those outdoors of potentially hazardous weather. Asperitas is now a cloud to watch out for too."

Clouds have always appeared in paintings, photographs and pictures, but images captured by amateur photographers confirmed the existence of a dramatic cloud form with a roughened, wavelike base.

This newly-recognised cloud was officially named asperitas by the World Meteorological Organisation in March, following a 10-year campaign for recognition by the UK-based Cloud Appreciation, led by Gavin Pretor-Pinney, a Visiting Fellow in the Department of Meteorology at the University of Reading.

The Reading-led researchers analysing the cloud for the new study compared sightings with available meteorological data from that time and location to investigate the that likely gave rise to the cloud formation.

They found that the asperitas formation is likely to be closely associated with atmospheric gravity waves. These are generated along weather fronts and by thunderstorms, where air masses clash and cause vertical motion. This was seen in some of the satellite images analysed by the scientists.

Explore further: Cloud spotters help 'wave-like' formation secure official recognition

More information: R. Giles Harrison et al. Asperitas - a newly identified cloud supplementary feature, Weather (2017). DOI: 10.1002/wea.2996

Related Stories

Clouds may have more of an impact on El Nino than thought

January 5, 2016

(—A small team of researchers from the U.S., Australia and Germany has found evidence that suggests cloud formation may have a much bigger impact on weather patterns associated with El Niño events than has been ...

Recommended for you

Propping up glaciers to avoid cataclysmic sea level rise

September 20, 2018

As global warming outpaces efforts to tame it, scientists have proposed building massive underwater structures to prevent an Antarctic glacier the size of Britain from sliding into the sea and lifting the world's oceans by ...

NASA balloon mission captures electric blue clouds

September 20, 2018

On the cusp of our atmosphere live a thin group of seasonal electric blue clouds. Forming 50 miles above the poles in summer, these clouds are known as noctilucent clouds or polar mesospheric clouds—PMCs. A recent NASA ...

Study tracks Hurricane Harvey stormwater with GPS

September 20, 2018

Hurricane Harvey dumped more than 5 feet (1.5 meters) of water on southeast Texas in late August 2017, making it the wettest recorded hurricane in U.S. history. But after the storm passed, where did all that water go?

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet May 10, 2017
"Citizen science has helped experts to explain how the newly-recognised 'wave-like' asperitas cloud is formed."

What is the literal meaning of the word "asperitas." I hope in some way it acknowledges the contribution of the "citizens" who aided the scientists.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.