( ( Jet stream ) ( ( -LRB- ( atmosphere -RRB- ) ) ( ( Jet stream ) ( ( is ( ( ( a band ) ( of ( fast-moving ( air currents ) ) ) ) ( that ( occur ( at ( high altitudes ) ) ) ) ) ) . ) ) ) )
(ROOT (S (NP (NNP Jet) (NN stream)) (PRN (-LRB- -LRB-) (NP (NN atmosphere)) (-RRB- -RRB-)) (NP (NNP Jet) (NN stream)) (VP (VBZ is) (NP (NP (DT a) (NN band)) (PP (IN of) (NP (JJ fast-moving) (NN air) (NNS currents))) (SBAR (WHNP (WDT that)) (S (VP (VBP occur) (PP (IN at) (NP (JJ high) (NNS altitudes)))))))) (. .)))
Jet stream (atmosphere) Jet stream is a band of fast-moving air currents that occur at high altitudes.
(ROOT (S (NP (NNP Jet) (NNP streams)) (VP (VBP are) (ADVP (RB fast)) (VP (VBG moving) (NP (NP (NNS rivers)) (PP (IN of) (NP (NN air))) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (VP (VBG going) (PP (IN in) (NP (NP (JJ opposite) (NNS directions)) (VP (VBN called))))))))))) (. .)))
Jet streams are fast moving rivers of air that are going in opposite directions called.