Scientists have reported that the jet stream is changing, bringing about marked changes in weather systems over the United States and Northern Europe.
Jet streams are fast moving, narrow bands of strong winds found in the upper part of the Earth's atmosphere. These jet streams are responsible for driving weather systems around the world. Scientists are particularly concerned about the polar jet stream, which affects the weather patterns in the northern parts of Europe and North America. In a recent yearly meeting of the American Association for the Advancement of Science, research professor of marine and coastal sciences Jennifer Francis from the Rutgers University in New Jersey warned that the jet stream is becoming longer and wavier. This phenomenon can explain the recent changes in weather in the northern parts of the world.
The jet stream can also be seen as a divider between cold air from the Arctic going down to the lower latitudes and warm air from the tropics moving up to the Arctic regions. Since storms have a tendency to move along the jet stream, these weather patterns can wreak havoc on areas located along the jet stream. The current changes in the jet stream can also be responsible for the polar vortex that hit North America this winter. Francis is stressing the importance of these recent changes to the current weather conditions being experienced in many Northern countries.
"It's important because the difference in temperature between the cold air in the polar vortex and warmer air outside of it drives the jet stream, a narrow, variable band of very strong, predominantly westerly air currents encircling the globe several miles above the earth - and the jet stream has a lot to do with our weather," says Francis. "In the Northern Hemisphere, the jet stream moves west to east in a wavy pattern."
The UK has been notorious for its very fickle weather. Due to the meandering of the jet stream however, the country has been experiencing long bouts with rain and extended periods of sunny weather. This current trend can be explained by the lengthening of the jet stream, which can cause weather to get stuck in certain areas for longer periods of time.
While the issues is one that directly affects climate and weather systems, Francis declined to point a finger at global warming and climate change.
"We can't say these extremes are happening because of climate change, but we can say that they're more likely because of climate change," says Francis. "Note that when a big trough occurs in one place, there is almost always a big northward swing of the jet stream -- called a ridge -- on either side. That is certainly the case now, and it is causing an unusually warm winter in Alaska, drought conditions in California and a particularly warm winter in Scandinavia as well."
