( ( As ( altitude increases ) ) ( , ( temperature ( decreases . ) ) ) )
(ROOT (S (PP (IN As) (NP (NN altitude) (NNS increases))) (, ,) (NP (NN temperature)) (VP (VBZ decreases)) (. .)))
As altitude increases, temperature decreases.
(ROOT (S (NP (NNP Air) (NN temperature)) (VP (VBZ changes) (PP (IN as) (NP (NN altitude) (NNS increases)))) (. .)))