Multiple choice Fast moving currents of air that occur above the friction layer are called mesocyclones wind trains jet streams chinoks Reveal answer Fill a bubble to check yourself C Correct answer Explanation Jet streams are narrow, fast-moving air currents in the upper atmosphere (above friction layer). They flow west to east and steer weather systems. Mesocyclones are storm rotations; 'chinoks' should be 'chinooks' (foehn winds).