Tuesday, April 24, 2012

Weird Weather Linked to Arctic Meltdown

Did readers in the northeast enjoy the late blast of winter after basking in 80 degree April sunshine? US Person endured two months of almost continuous cold and rain in March and April here in the northwest. So what's up with the weird weather? Besides the usual suspects like La Niña, and El Niño, scientists are becoming aware of the impacts of "Arctic Amplification" the alterations in the jet stream caused by a rapidly warming Arctic region. The Arctic has lost 40% of its ice cover in summer in just three decades. The jet stream is a river of moving air that flows between 30 north latitude and 60 degrees, separating cold air from warm. As the arctic melts the temperature difference lessens which changes the jet stream in two ways. The west to east speed of the jet streams slows. Over the North Atlantic wind speeds have dropped by about 14% since 1980. That allows weather systems to persist leading to phenomena of heavier snowfalls and longer periods of cold or hot weather. Deep troughs in the jet stream persisted over the East coast during the winters of 2009-10 and 2010-11, bringing record snow fall amounts and very cold weather. This winter has been unusually warm in the northeast with much less snow fall because the region was under a ridge or northward bulge of the jet stream. At the same time in Alaska a deep trough dumped record amounts of snow. Secondly, the perturbations in the stream or 'waviness' increases allowing the intrusion of tropic air farther north, "ridges", and arctic air farther south, "troughs". These waves of air often lead to record breaking temperatures. Predicting long range weather patterns is difficult work, but a safe conclusion is that as the Earth continues to warm up because of man's activities, weather will get more "weird".