( ( Remembering ( that ( pressure ( decreases ( as ( altitude increases ) ) ) ) ) ) ( , ( ( ( a relationship ) ( between ( ( pressure and ) altitude ) ) ) ( ( is established ) . ) ) ) )
(ROOT (S (S (VP (VBG Remembering) (SBAR (IN that) (S (NP (NN pressure)) (VP (VBZ decreases) (PP (IN as) (NP (NN altitude) (NNS increases)))))))) (, ,) (NP (NP (DT a) (NN relationship)) (PP (IN between) (NP (NN pressure) (CC and) (NN altitude)))) (VP (VBZ is) (VP (VBN established))) (. .)))
Remembering that pressure decreases as altitude increases, a relationship between pressure and altitude is established.
(ROOT (S (NP (NNP Air)) (VP (VBP pressure) (SBAR (S (NP (PRP it)) (VP (VBZ decreases) (PP (IN as) (NP (NN altitude) (NNS increases))))))) (. .)))