The Jet Stream

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The Jet Stream is "relatively strong winds concentrated in a narrow stream in the atmosphere, normally referring to horizontal, high-altitude winds. The position and orientation of jet streams vary from day to day. General weather patterns (hot/cold, wet/dry) are related closely to the position, strength and orientation of the jet stream (or jet streams). A jet stream at low levels is known as a low-level jet." The jet stream often serves as steering mechanism for upper level and lower level storm centers in the atmosphere. You may here the jet stream referred to as a "thermostat." This is because the contrasting air masses around the globe are shaped and guided by the jet stream. In general, regions north of the jet stream experience cold weather while locations south of the main jet stream experience warm weather. At any given time there are several jet streams encircling the globe, including the Polar Jet and the Subtropical Jet.