( ( When ( ( ( these winds ) ( which ( contain ( the water ) ) ) ) ( hit ( the ( mountain range ) ) ) ) ) ( , ( ( the winds ) ( ( are ( forced upward ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (DT these) (NNS winds)) (SBAR (WHNP (WDT which)) (S (VP (VBP contain) (NP (DT the) (NN water)))))) (VP (VBD hit) (NP (DT the) (NN mountain) (NN range))))) (, ,) (NP (DT the) (NNS winds)) (VP (VBP are) (VP (VBN forced) (ADVP (RB upward)))) (. .)))
When these winds which contain the water hit the mountain range, the winds are forced upward.
(ROOT (S (NP (NN Chinook) (NNS winds)) (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (NN air)) (VP (VBZ is) (VP (VBN forced) (PP (IN over) (NP (DT a) (NN mountain) (NN range)))))))) (. .)))