![]() ![]() – The Latest: Oklahoma gov seeks federal disaster declaration.– Power outages linger for millions as another icy storm looms.Even as these outbreaks of cold Arctic air to mid-latitudes happen, the overall warming of Arctic temperatures will likely mean that these cold air events will become less extreme. I t is currently uncertain from the observational record whether these meanderings of the jet stream are becoming more or less frequent, and there is an active debate within the scientific community on this topic. Mid-latitude extreme cold events will continue to happen because of natural variability in the climate system. The effects of Arctic warming and sea ice loss on the polar jet stream aren’t fully understood, but it’s possible that more frequent visits of polar air to mid-latitudes could occur as a result of these changes. This rapid warming has already been linked to sea ice losses in the Arctic, and scientists are exploring the effects of these changes across other parts of the planet. The pattern is further complicated by the overall warming of the Arctic, which is occurring at a faster rate than for other areas of the planet. When the polar jet stream develops a more wavy or meandering pattern, cold Arctic air can spill southward to mid-latitudes.Ī Warming Arctic Complicates This Pattern When the polar jet stream meanders southward across the United States, the cold polar air can push as far south as Texas and the Gulf Coast. The meandering causes the large mass of cold air situated at high altitudes over the Arctic to wobble, and, like a toupee that goes askew, cold polar air can slip southward to affect locations in the United States, Europe, and Asia. ![]() While the polar jet stream tends to mark the boundary between warmer air at lower latitudes and the colder air that often remains contained over the Arctic, the polar jet stream can sometimes develop a more “wavy” or meandering pattern. A complex combination of factors sets up these interactions between cold Arctic air and the mid-latitudes. The polar jet stream is the culprit affecting mid-latitude winter weather. Gardiner/UCAR Meanders in the Polar Jet Stream Can Bring Cold Arctic Air South The light purple indicates the location of the polar jet stream during a time when meanders form and the cold, Arctic air (white) dips down to the mid-latitudes. The stratospheric polar vortex and the tropospheric polar jet stream can interact, but the polar jet stream also varies in association with weather events and large-scale atmospheric circulations.ĭark purple arrows indicate the counterclockwise direction of rotation of the polar vortex in the Arctic. The polar jet stream occurs in the troposphere at altitudes of 8-14 km (5-9 miles). The polar vortex is a band of strong westerly winds located 16-50 kilometers (10-30 miles) above Earth’s surface in the stratosphere. But what is the polar jet stream? It is easy to confuse the polar jet stream with the term “polar vortex,” but they are not the same thing. The polar jet stream, which marks the boundary between cold polar air and warmer mid-latitude air, can dip south from its usual perch circling the Arctic and bring freezing cold temperatures. Every once in a while, cold Arctic air comes to visit the mid-latitudes. ![]()
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