The term "jet stream" is often used by weather forecasters to describe A: The cloud-like condensation trails that are sometimes seen behind jet aircraft.
B: Warm pacific winds associated with volcanic activity in the western pacific which carry heat to the north pole
C: Solar winds that bring high energy particles to the upper atmosphere, providing heat which sets off convection cycles disturbing weather in the tropical latitudes
D: The west to east winds that circle the globe, often just below the poles in latitude and just beneath the stratosphere in elevation