MetLink - Contact Message 5 - 1999

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Ice and snow in the UK and transport probems!

From: education@royal-met-soc.org.uk
Subject: Ice and snow in the UK!
Date: Tue, 9 Feb 1999 11:10:17 -0000

Dear MetLink friends

Here at the Royal Meteorological Society at 0800 UTC this morning (9 Feb, 1999), the temperature was -2 deg C and the wind was blowing from the north at about 10 km/h. Before I could come to work, I had to clear not only a 'dusting' of snow from the car but also a layer of ice. The raindrops which were on the car last night had frozen! We have, at last, had a taste of winter weather! But the sun is shining. It's a beautiful day for taking a walk in the country, not sitting in a centrally-heated office! However, reporting on the weather in Reading today is not really why I am writing to you on this occasion.

I am wondering why, in the UK, we put salt and grit on roads BEFORE snow falls? In my experience, the slip-streams behind vehicles blow most of the salt and grit into the gutters at the sides of the roads, whence it runs off into drains. Thus, it seems to me, the exercise is wasteful. Some years ago, I spent a winter in New York, USA, and there, so I was told, the custom was to put down salt and grit only when snow started to fall. The reason was that the said salt and grit would 'stick' to the snow and not be wafted to the sides of the roads. Indeed, the folk in New York could not understand why we in Britain put down salt and grit BEFORE snow falls. Have any MetLink participants any views on this matter? Would anyone like to explain why one practice may be better than another?

Do you know that Toronto (Canada) has a network of high-speed roads somewhat like the network of freeways in and around Los Angeles? I wonder if your students can suggest the 'worst possible weather scenario' for traffic chaos in Toronto. Well, so I am told ..... it's a very, very light snowfall -- note VERY light -- occurring about 1500 local time. The snow collects in the dimples on the road surface and the traffic smoothes the surface, which therefore becomes very slippery indeed. If a heavier snowfall occurs, drivers can see there is snow and drive with appropriate caution. Accordingly, the problem is not merely a meteorological one. Driver perception is involved, too. When drivers think the surface is dry, they drive fast, not realising there is compressed snow in the dimples of the road. Accidents then easily occur. Perhaps you would like to explore with your students the subject of driver perception in relation to various types of weather.

One more point ..... At what temperature is ice (including snow) most slippery? I believe the answer is 0 deg C. Why should this be so? Why 0 deg C?

Best regards Malcolm

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2 ... WATER SUPPLIES AND USAGE

Without air, water and food, humans cannot survive. We can live without clothes or shelter in some parts of the world, but nowhere can we live without air, water and food. Let us focus on water. Where do your water supplies come from? In Malta, for example, you have long dry periods in summer. Where does your drinking water come from? Underground aquifers? Do you have restrictions on water consumption at any time of year? And on Tristan da Cunha, you probably have special arrangements for collecting rain and storing it. Please send us some information. What problems of water supply do you have in other parts of the MetLink world? Please tell us. The UK is a comparatively wet part of the world, as you no doubt know, but even here we have water-supply problems. In the summer of 1976, after more than a year of below-average rainfall (generally below 50% of normal), many parts of England and Wales, like other parts of north-west Europe, had restrictions on water usage imposed; and in south-east Wales, water was actually cut off for 17 hours a day for several weeks. In recent years, too, there has been below-average rainfall in southern Britain and streams have dried up. In recent weeks, however, the weather has made up for the rainfall deficiencies of recent years. As our friends at Pennar School told us this week, Britain has been rather wet lately.

And what use do you make of water, other than drinking it and using for various industrial purposes? Do you use it to generate power? I'm sure you do in Scandinavia, but how much power is hydro-electric? Is it as much as 98% of all power in Norway? To what extent is the melting of winter snow helpful for maintaining supplies of hydro-electric power? Do any of you in the MetLink world use wind power? Do any of you use power from sea waves or tides? I think you do in Norway -- am I correct? If so, where is such power generated, and how much power?

That's all for now. I hope these ideas are helpful.

Best regards Malcolm

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