Jetstream

From Wikipedia

Jet streams are fast flowing, narrow air currents found in the atmospheres of some planets. The main jet streams are located near the tropopause, the transition between the troposphere (where temperature decreases with height) and the stratosphere (where temperature increases with height). 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.