( ( The ( atmospheric pressure ) ) ( ( decreases ( with altitude ) ) . ) )
(ROOT (S (NP (DT The) (JJ atmospheric) (NN pressure)) (VP (VBZ decreases) (PP (IN with) (NP (NN altitude)))) (. .)))
The atmospheric pressure decreases with altitude.
(ROOT (S (NP (NNP Air)) (VP (VBP pressure) (SBAR (S (NP (PRP it)) (VP (VBZ decreases) (PP (IN as) (NP (NN altitude) (NNS increases))))))) (. .)))