TOP 100 SCIENCE SITES
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| Supercomputer to boost research output The most powerful supercomputer in the country is now online at the Australian National University (ANU) in Canberra. abc.net.au |
Don't blame fast food: Mummies had heart disease ORLANDO, Fla. (AP) -- You can't blame this one on McDonald's: Researchers have found signs of heart disease in 3,500-year-old mummies.... hosted.ap.org |
Trial to root out new biofuel source Researchers say they are excited by a new source of biofuel currently being grown in southern Queensland's Lockyer Valley. abc.net.au |
Famous San Francisco sea lions leave in droves SAN FRANCISCO (AP) -- Two mysteries surround a huge herd of sea lions that were hanging out on a pier in San Francisco Bay: Why did so many show up, and why did so many leave at once?... hosted.ap.org |
The right and wrong types of snow It can blanket the ground, or melt on impact. A lot can depend on when and where it fallsThe snowy scenes of a winter wonderland can be harder to create than you may think. There is the type of snow for starters. While rail operators are routinely lampooned for blaming inappropriate varieties of snow for the breakdown of their equipment, the white stuff does come in many shapes and sizes, which do behave differently.Then there is the heat content and shape of the ground, which can influence the intensity and duration of the snowfall. Moisture in the air plays a role, as does the temperature. Finally, whether it is day or night can influence whether the snow sticks around or melts away. Call it the wrong time of snow. All of which helps to explain why, as the majority of the country today struggled and snowballed its way through a day of blizzards and gritting, workers in central London who looked out of their office windows could be forgiven for wondering what the fuss was about. As the Guardian went to press, the snow that did fall on the capital had generally failed to settle.So what went right?Ewen McCallum, chief meteorologist at the Met Office in Exeter, said: "The snow in London came down during the day and was not particularly heavy. The temperature of the ground would have been warm enough to melt the snow before it could settle." The snow that blanketed the south-west was similar to the falls in London, McCallum said, but came at 4am. Even the meagre sunlight of a winter's day is enough to lift the temperature of the pavements and roads of a city.Then there is the urban heat island effect, with all the industry and concrete surfaces acting as giant radiators.The best time for snow to fall and settle on London is during the night, as happened last February.The colder air of a nighttime snowfall encourages drier, powdery snow – the type beloved by skiers and snowboarders and dreaded by rail companies.Wetter snow, easy to spot as the falling individual flakes clump together into bigger chunks, comes when the air temperature is higher. Much higher still, and the wet snow turns to sleet and then rain.At the other end of the temperature spectrum, can it really, as you will inevitably hear, be too cold to snow?"I've heard that one before," McCallum sighed. "The answer is no – but there is a but." Extremely cold conditions are often down to a lack of water in the atmosphere, which means fewer clouds, and so less snow.WeatherMeteorologyDavid Adamguardian.co.uk © Guardian News & Media Limited 2010 | Use of this content is subject to our Terms & Conditions | More Feeds guardian.co.uk |