Meteorologists believe that the jet stream, which drives the weather over northern Europe and the United States, is changing -- and our weather is changing with it.
At the annual meeting of the American Association for the Advancement of Science in Chicago, Jennifer Francis of Rutgers University in New Jersey said: "People are noticing that the weather in their area is not what it used to be."
The culprit, she believes, is a longer, more meandering jet stream. The jet stream separates warm air masses moving poleward from the tropics and cold air masses moving southward from the poles. Storms tend to track along it, so when it lies directly over Britain, as it has for much of winter 2013/14, the country is directly in the firing line.
The strength of the jet stream is directly proportional to the difference in temperature between the poles and the tropics. When it's strong, the jet stream tends to take a straighter path, but when it's weak it meanders. As the Arctic is experiencing warming at faster rates than the tropics, that difference is getting smaller, so the jet stream is weakening along with it.
What that means for mid-latitudes, where Britain is located, is weather that stays in place for longer. Weather patterns will be more likely to get 'stuck' over a location, yielding long periods of rain and sun rather than Britain's traditional 'changeable' skies. "We can expect more of the same and we can expect it to happen more frequently," said Francis. However she declined to pin the blame on man-made climate change. "The Arctic has been warming rapidly only for the past 15 years," she said. "Our data to look at this effect is very short and so it is hard to get a very clear signal."
This article was originally published by WIRED UK
