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Dr Graeme Marlton explains how different clouds are named and why cloud classification matters in a new post for The Conversation.

Image credit: Cliff CooperCC BY 2.0 

Clouds form in a multitude of different shapes and sizes, their infinite combinations and position across the sky offering a visual drama in response to the light conditions. But despite their apparent randomness, a detailed naming convention is in place to categorise them.

When a cloud ultimately can’t be fitted into one of the many existing categories, it can be nominated for a classification of its own. In 2017, the World Meteorological Organisation (WMO) added 12 new types of cloud to the International Cloud Atlas, the world standard guide for cloud classification. And I worked as part of a small team investigating the science behind one newly categorised cloud, Asperitas, which exhibits wave-like perturbations, reminiscent of a rough sea in the base of the cloud.

Clouds are named using a Latin-based system proposed by Luke Howard in 1803, which laid the foundations for the WMO cloud atlas in 1939. Clouds are separated into ten basic genera, which are shown in the image below, and are described by their shape and altitude.

For example, Cumulus, from the Latin for heaped or puffed, describes clouds with a “cotton wool” appearance. Stratus describes a low-level layer cloud with a uniform, even base that covers much of the sky. Nimbus means rain-bearing, so a cloud called Nimbostratus is a layer cloud that produces rain or, sometimes, snow.

Read the rest of this post and see images of the different cloud types on The Conversation, where this piece was first published on 27 March 2018. Dr Graeme Marlton is a Postdoctoral Researcher in the University of Reading’s Meteorology department.

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Clouds could be given a helpful jolt of electric charge to increase much-needed rainfall in dry parts of the world, thanks to an award-winning research proposal by scientists at the University of Reading.

The new study will investigate how charge modifies the growth of tiny water droplets into larger drops that fall as rain. It will use a supercomputer to simulate the cloud processes in detail, with specially developed robotic aircraft to sample and charge the clouds.

The Reading team was one of three groups awarded funding in this year’s US $5-million-dollar United Arab Emirates (UAE) Research Program for Rain Enhancement Science, at a ceremony in Abu Dhabi on Tuesday 17 January. Reading will receive US $1.5m.

The story has been given wide coverage in the region’s media. Read news story in ‘The National

 

Professor Giles Harrison is interviewed at the ceremony in Abu Dhabi

Giles Harrison, Professor of Atmospheric Physics at the University of Reading, said: “Our project is about changing the balance of charges on the tiniest cloud droplets, a neglected aspect of clouds which could revolutionise our ability to manipulate rainfall in areas that need it most.

“The UAE’s programme is ambitious and imaginative, and has already brought many international scientists together on this important topic.”

READ MORE on our News website >

The new research proposal was based on a study published in the Quarterly Journal of the Royal Meteorological Society in May 2015.

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