Given a jet core, the area where the speed increases markedly upstream is referred to as the jet entrance region.
Given a jet core, the area where the speed decreases markedly downstream is referred to as the jet exit region.
A small-scale but intense core of strong winds, usually within (and moving quickly along) a well-defined jet stream (See "What are jetstreams?"). They generally do not have a length much more than two to three-hundred kilometres, and can be associated with explosive cyclogenesis events (q.v.). Difficult to pick up via conventional observations (e.g. radiosonde wind-finding), but can be detected in WV imagery. (See also "What are the various types of satellite imagery available?")
A band of high winds usually found in the upper troposphere: wind speeds can exceed 90 m/s. Jet streams are also located in the stratosphere and, with lower speeds, in association with the atmospheric boundary layer. (See also "What are jetstreams?").