( ( ( ( Sometimes ( ( ( the crests ) ( of ( one wave ) ) ) ( ( ( ride ( on ( ( the crests ) ( of ( the ( other wave ) ) ) ) ) ) , ) ( creating ( enormous crests ) ) ) ) ) -- ) ( ( an effect ) ( called ( constructive interference ) ) ) ) . )
(ROOT (S (S (ADVP (RB Sometimes)) (NP (NP (DT the) (NNS crests)) (PP (IN of) (NP (CD one) (NN wave)))) (VP (VBP ride) (PP (IN on) (NP (NP (DT the) (NNS crests)) (PP (IN of) (NP (DT the) (JJ other) (NN wave))))) (, ,) (S (VP (VBG creating) (NP (JJ enormous) (NNS crests)))))) (: --) (S (NP (DT an) (NN effect)) (VP (VBD called) (NP (JJ constructive) (NN interference)))) (. .)))
Sometimes the crests of one wave ride on the crests of the other wave, creating enormous crests--an effect called constructive interference.
(ROOT (S (NP (NP (DT The) (JJ high) (NNS points)) (PP (IN in) (NP (DT a) (JJ transverse) (NN wave)))) (VP (VBP are) (VP (VBN called) (NP (NNS crests)))) (. .)))