AUGUSTA, GA (WFXG) - Mark Twain is famous for writing: If you don't like the weather, just wait a few minutes. Weather is always changing and a lot of that change comes from the jet stream.
The jet stream is a fast moving current of air several miles above us that wraps around the entire globe. When we mention the jet stream, we're actually talking about two different rivers of air, the polar jet and the subtropical jet.
The polar jet tends to be the stronger of the two, so that's the one we focus on most often when talking about weather.
The jet stream runs from west to east but doesn't run in a straight line. It meanders north and south as it wraps around the globe and acts as a steering current for weather systems. The jet stream is often a dividing line between cold and warm air.
Where it sets up changes with the seasons. In the summer, you can typically find it near the U.S. – Canadian border while in the winter, it moves further south into the U.S.