. . . . . "Jet streams are fast flowing, narrow air currents found in the atmosphere of some planets, including Earth. The main jet streams are located near the altitude of the tropopause. The major jet streams on Earth are westerly winds (flowing west to east). Their paths typically have a meandering shape; jet streams may start, stop, split into two or more parts, combine into one stream, or flow in various directions including the opposite direction of most of the jet."@en .