( ( Maritime ( Polar ( Air ( Mass ( ( -LRB- ( mP -RRB- ) ) Air ) ) ) ) ) ( ( ( ( mass ( that forms ) ) ( over ( ( extensive ( ocean areas ) ) ( of ( the middle ) ) ) ) ) ( to ( high latitudes ) ) ) . ) )
(ROOT (S (NP (NNP Maritime) (NNP Polar) (NNP Air) (NNP Mass) (PRN (-LRB- -LRB-) (NP (NN mP)) (-RRB- -RRB-)) (NNP Air)) (VP (VBD mass) (NP (DT that) (NNS forms)) (PP (IN over) (NP (NP (JJ extensive) (NN ocean) (NNS areas)) (PP (IN of) (NP (DT the) (NN middle))))) (PP (TO to) (NP (JJ high) (NNS latitudes)))) (. .)))
Maritime Polar Air Mass ( mP ) Air mass that forms over extensive ocean areas of the middle to high latitudes.
(ROOT (S (SBAR (IN If) (S (NP (DT an) (NN air) (NN mass)) (VP (VBZ forms) (PP (IN over) (NP (DT an) (NN ocean)))))) (NP (PRP it)) (VP (VBZ is) (VP (VBN called) (NP (DT a) (JJ maritime) (NN air) (NN mass)))) (. .)))