Wetenschap - 17 januari 2013

Wageningen, for the quality of ice

Technical tools give the weather a hand.
'The ice doubled in thickness in one hour.'

9-ijsmaker-BdG_0563.jpg
9-ijsmaker-BdG_0563.jpg

Foto: .

The pond next to Lumen is frozen solid. That had already happened on Sunday night. A typical winter scene. Although... typical? Part of the bridge has been wrapped in aluminium foil. An experiment by meteorologist Bert Heusinkveld. He wants to show that ice grows faster if you give nature a helping hand.
Heusingveld's theory and experiment are simple. Frost is a matter of heat transportation, in this case heat radiation in the form of infrared. Under the bridge that heat cannot escape as easily as elsewhere on the pond. In Heusingveld's words, there is no clear view of the sky. With the help of the reflective foil, the radiation can escape better. Voila: a way to get rid of gaps in the ice under the bridge more quickly. Cheap and easy.
Dry ice
Heusingveld is going to drill to show how ice develops. In technical terms, this is child's play. But it is 'proof of principle', stresses Heusingveld. It is just a hobby at the moment. But a hobby with a purpose. Heusingveld and his colleagues at Meteorology and Air Quality have been trying to get the NWO to warm to the idea of a PhD research on improved modelling of ice growth.
'Ice master' Heusingveld was in the world news briefly last year with his idea for speeding up ice growth by pouring dry ice (solid carbon dioxide) onto it. This works, demonstrably. 'The temperature of dry ice is minus 80 degrees. The ice doubled in thickness in one hour. You could hear it crackling, it went so fast.' But the board of the Dutch elfstedentocht (the eleven towns skating race) was not interested. 'They think the ice has to be natural. As if ice transplantation were natural!'
Elfstedentocht board
So Heusingveld and his colleagues are now focusing their efforts on a project to get to grips with ice growth. The current models are already 20 years old. They do come from Wageningen, but are due for an update. 'They do not include the soil temperature, for instance. Nor the currents you get in strong winds. That is typical Wageningen knowledge.' Better models make it easier to predict ice growth.
But the Elfstedentocht board is holding off at the moment. A talk with the board last year generated sympathy but no funding for further tests. Pity, says Heusingveld. 'Technically, there are all sorts of solutions you could come up with to speed up the growth of ice and make an elfstedentocht possible sooner. But they don't want to.' He does understand their point of view, though. 'Of course part of the charm is that it is so old-fashioned.' 

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