'Ice lollies' found in UK clouds

'Ice lollies' found in UK clouds

Wed, 28/06/2017 - 13:27
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Clouds aren’t typically associated with ice lollies, but rather sunshine – until now. Researchers from Manchester University have found ice lolly-shaped icicles in cloud systems over the UK and the North Atlantic.

The ice formations – which are the shape of a stick attached to a large spherical head – were found in large concentrations during a research flight over the northeast Atlantic Ocean in 2016, and previously in southwest UK in 2009.

The research, which is published in Geophysical Research Letters in May this year, explored the unique measurements collected from probes on-board the research aircraft combined with data from ground-based radars (for the 2009 UK data).

The ice lollies evident in 2009 were typically around a millimetre long and found at an altitude of between 1 and 2.3 kilometres. They formed when a belt of rising humid air moving up through clouds generated supercooled water droplets that collided with falling stick-shaped ice particles that were created by the splintering and accretion of frozen water in the tops of the clouds.

Stavros Keppas - one of the research team – suggests that these ‘Ice lollies’ alter the balance between liquid water and ice in clouds, which may affect a clouds’ lifetime and thus their reflectivity and ability to produce precipitation.

Keppas thinks that features may form on a regular basis, especially at high latitudes, but that ‘more measurements are needed’ in this region of a cloud system to determine whether it is a widespread phenomenon, and its importance in the climate system.

Usually many small droplets are attached to an ice crystal during such events, rather than one larger droplet, therefore these features may help shed light on processes active in clouds.