sentence2_structure: Jet streams<>are fast moving<>rivers of air that are going in opposite directions$$$rivers of air<>are going<>in opposite directions$$$opposite directions<>called<>
sentence1: Generally, storms move with the direction of the upper-level jet stream.
sentence2: Jet streams are fast moving rivers of air that are going in opposite directions called.
question: What are fast moving rivers of air that are going in opposite directions called?