Ever wondered why ice is sometimes slippy and other times not?

A geoscientist from the University of Sheffield has explained why some of the ice caused by the Arctic conditions this month is slippy and other times it is almost grippy underfoot.

glacier with Professor Clark

Expert Professor Chris Clark, of the University of Sheffield’s Department of Geography, says the freezing temperatures – which have reached as low as -13ºC in the UK – has created “sticky” cold ice.

However, when the ice starts to melt, at about -1 ºC to 0ºC, the “warm ice” has a thin layer of meltwater on its surface and becomes slippy, transforming the countries footpaths and roads into ice rinks.

Professor Clark, who is leading a £3.7 million ice sheet and sea level research project, said: “Most people think of of ice as cold. Those who know ice know that some is cold and some is warm. Cold ice, say minus five is actually fairly grippy, like when you take an ice cube out of freezer it will often even stick to your hand.

“Warm ice, say at minus one or nearly zero will have a thin film of meltwater on its surface, and it is this that makes it so slippy. It also looks different, less frosty, when it gets near to melting, that is how a good glaciologist knows to take shorter steps so they don't slip over on the pavement.”

Professor Clark – one of many world leading experts on glaciers and ice sheets at the University Department of Geography – also has a helpful hint for car driving commuters who will be no strangers to the effects of ice on their windscreens in the early hours of the morning.

“Sometimes it is like glue and hard to budge and other times when near zero you can just slide it off”, added Professor Clark. “The best trick for clearing a windscreen is fun but can be painful! Place the palm of your hands on the screen and melt it. If you’re feeling tough do it on the outside, or, if not, do it on the inside. It raises the temperature to near melting and then the ice simply slides off because you have melted the ‘glue’.

“Many glaciers have such cold ice that this adheres or glues them to the bedrock beneath. Some, on the other hand have warm slippy ice at the bed and these ones flow much faster. So an understanding of how to walk on iced pavements helps understanding glaciers.”

Additional information

University of Sheffield’s Department of Geography

For more information on the Department of Geography please visit: http://shef.ac.uk/geography

The University of Sheffield

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For further information please contact:

Paul Mannion
Media relations officer
The University of Sheffield
0114 222 9851