( This ( ( causes ( ( the ( water ( vapor molecules ) ) ) ( to ( slow down ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ causes) (S (NP (DT the) (NN water) (NN vapor) (NNS molecules)) (VP (TO to) (VP (VB slow) (PRT (RP down)))))) (. .)))
This causes the water vapor molecules to slow down.
(ROOT (S (PP (IN As) (NP (NP (DT the) (NN temperature)) (PP (IN of) (NP (NN water) (NNS decreases))))) (, ,) (NP (DT the) (NN water) (NNS molecules)) (VP (VB slow) (PRT (RP down))) (. .)))