( ( Air density ) ( ( decreases ( with ( increasing temperature ) ) ) . ) )
(ROOT (S (NP (NNP Air) (NNP density)) (VP (VBZ decreases) (PP (IN with) (NP (VBG increasing) (NN temperature)))) (. .)))
Air density decreases with increasing temperature.
(ROOT (S (SBAR (IN As) (S (NP (DT the) (NN altitude)) (VP (VBZ decreases)))) (, ,) (NP (NP (DT the) (NN density)) (PP (IN of) (NP (NN air)))) (VP (VBZ decreases)) (. .)))