Here in the UK we are not quite used to the severe weather conditions encountered of late. Sub-zero temperatures and the heaviest snowfalls for almost thirty years have brought the country to a standstill and forced residents to retreat to the warmth and security of their homes.
Streets are deserted, rural towns and villages cut off from main road and rail connections and supermarkets low on supplies. In some parts of the world, 21st Century Britain resembles a snapshot from some futuristic disaster novel!
So while the rest of the world chuckles at us in our state of unprepared panic, I thought I would take a look at a natural condition that in a matter of hours, can bring one of the most developed and civilised nations on the planet to a virtual standstill. Great Britain on 7th January 2010 from space:
Snow blanketed Great Britain on 7th January 2010, as the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite passed overhead and captured this image. (source: spacefellowship.com & NASA)
Snow!what is it? What creates it and what exactly makes it fall?
Well, it might seem like an obvious statement to make but to start with, snow isn’t just a bi-product of the cold.
To start with, in its purest form, snow is made up of soft crystals, infinite in shape and variety and very difficult to analyse. Although snow falls mainly in winter, snowflakes themselves form throughout the year with most of them falling like rain. Even in the summer, the wet weather we experience is in fact melted snow.
As a leading scientist explained to me, air temperature decreases with height and the amount of water vapour the air can hold is proportional to the temperature. So, the warmer the air, the more moisture it can hold. Consequently, if the temperature drops below freezing this water vapour changes directly to ice and from here ice crystals are born.
Once the ice crystals have formed they start to fall and as they drift so they collide. When large crystals collide they often shatter and these collisions release tiny splinters of ice. The best temperature for this process to work under is around minus five degrees and very large snowflakes form at this point. Colder conditions produce smaller snowflakes and powdered snow – the kind that produces the best consistency for skiing – is created in very cold clouds.
As the snow falls through the air, if the temperature rises above freezing then it will naturally begin to melt and eventually fall as rain. Furthermore, if it falls as snow, it will not settle unless the temperature in the air below the cloud base and on the ground is below four degrees.
Once fallen, snow packs together under its own weight and becomes denser by squeezing out the air between the grains. Wet snow contains three to six per cent water and is dense and heavy, making it the best type of snow for snowballs but not as good for skiing.
So in simple terms, there is a “wrong kind” of snow.
Of course, this does little to detract from the fact that such a simple process of nature can cause such disruption and in the UK at least, we are completely unprepared, even though we suffered similar issues less than twelve months ago!
Until the current cold snap passes – and we are told it could be with us for some time yet – I suppose the best solution might be to barricade the front door, dish out the hot chocolate, stick a DVD on the television and sit it out.
Below there is a list of facts relating to snow that many of you might not know:
Every snowflake has its own unique shape and no two flakes are the same.
All snowflakes have six sides.
Snowflakes aren’t always white. Years ago when coal was used in factories and homes, snow was often grey because the coal dust would enter the air and was absorbed by the clouds. In some parts of Canada where the soil is red clay, the snowflakes often look pink because of the same reason.
The largest snowflakes ever recorded fell in the state of Montana in the United States of America. The snowflakes were fifteen inches in diameter.
The average snowflake falls at a speed of 3.1 miles per hour.
Snirt is dirty snow that flies off the dusty Canadian prairies.
People buy more cakes, cookies and sweets than any other food when a blizzard is in the forecast.
A blizzard occurs when you can’t see for a quarter of a mile. The winds are always thirty-five miles an hour or more. The storm must last at least three hours to be classed as a blizzard. If any of these conditions are less, it is only a snowstorm. Billions of snowflakes fall during one short snowstorm.