This jet may not be marked by pronounced surface temperature contrasts but rather by relatively strong temperature gradients in the mid-troposphere. Moreover, when the polar-front jet penetrates to subtropical latitudes, it may merge with the subtropical jet to form a single band. Also peculiar to the tropical latitudes of the Northern Hemisphere is a high-level jet called the tropical easterly jet stream. Such jets are located about 15 N over continental regions due to the latitudinal heating contrasts over tropical landmasses that are not found over the tropical oceans. Positions of jet streams in the atmosphere.
Arrows indicate directions of mean motions in a meridional plane.
The general location of all three jet streams in relation to other mean meridional circulation features is shown in above figure. Jet streams occur in both hemispheres.