( ( Because ( ( atmospheric pressure ) ( ( decreases rapidly ) ( with ( altitude ( near ( the surface ) ) ) ) ) ) ) ( , ( ( ( a ( small change ) ) ( in elevation ) ) ( ( ( will often ) ( ( produce ( a ( significant change ) ) ) ( in ( air pressure ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Because) (S (NP (JJ atmospheric) (NN pressure)) (VP (VBZ decreases) (ADVP (RB rapidly)) (PP (IN with) (NP (NP (NN altitude)) (PP (IN near) (NP (DT the) (NN surface)))))))) (, ,) (NP (NP (DT a) (JJ small) (NN change)) (PP (IN in) (NP (NN elevation)))) (VP (MD will) (ADVP (RB often)) (VP (VB produce) (NP (DT a) (JJ significant) (NN change)) (PP (IN in) (NP (NN air) (NN pressure))))) (. .)))
Because atmospheric pressure decreases rapidly with altitude near the surface, a small change in elevation will often produce a significant change in air pressure.
(ROOT (S (NP (NNP Air)) (VP (VBP pressure) (SBAR (S (NP (PRP it)) (VP (VBZ decreases) (PP (IN as) (NP (NN altitude) (NNS increases))))))) (. .)))