( ( Since ( the ( Northeast ( United ( States ( and ( Nova Scotia ) ) ) ) ) ) ) ( ( , ( ( Canada ( are ( ( the ( last ( land locations ) ) ) ( as ( ( air masses ) ( ( move out ) ( over ( the ocean ) ) ) ) ) ) ) ) , ) ) ( measurements ( ( were ( ( made ( ( a number ) ( of ( land ( and ( island sites ) ) ) ) ) ) ( in ( ( ( ( ( Maine , ) ( Nova Scotia ) ) , ) and ) ( Sable Island ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Since) (NP (DT the) (NNP Northeast) (NNP United) (NNPS States) (CC and) (NNP Nova) (NNP Scotia))) (PRN (, ,) (S (NP (NNP Canada)) (VP (VBP are) (NP (NP (DT the) (JJ last) (NN land) (NNS locations)) (SBAR (IN as) (S (NP (NN air) (NNS masses)) (VP (VBP move) (PRT (RP out)) (PP (IN over) (NP (DT the) (NN ocean))))))))) (, ,)) (NP (NNS measurements)) (VP (VBD were) (VP (VBN made) (NP (NP (DT a) (NN number)) (PP (IN of) (NP (NN land) (CC and) (NN island) (NNS sites)))) (PP (IN in) (NP (NP (NNP Maine)) (, ,) (NP (NNP Nova) (NNP Scotia)) (, ,) (CC and) (NP (NNP Sable) (NNP Island)))))) (. .)))
Since the Northeast United States and Nova Scotia, Canada are the last land locations as air masses move out over the ocean, measurements were made a number of land and island sites in Maine, Nova Scotia, and Sable Island.
(ROOT (S (NP (NP (DT The) (JJS best) (NN explanation)) (PP (IN for) (SBAR (WHADVP (WRB how)) (S (NP (NN air) (NNS masses)) (VP (VBP move) (PP (IN across) (NP (DT the) (VBN united) (NNS states)))))))) (VP (VBZ is) (SBAR (IN that) (S (NP (DT the) (VBG prevailing) (NNS westerlies)) (VP (VP (VBP move) (NP (NN air) (NNS masses)) (PP (IN from) (NP (NN west))) (PP (TO to) (ADJP (JJ east))) (PP (IN across) (NP (DT the) (VBN united) (NNS states)))) (CC but) (VP (MD may) (VP (VB be) (VP (VBN deflected) (PP (IN by) (NP (DT the) (NN jet) (NN stream)))))))))) (. .)))