( ( As ( ( the air ) ( is lifted ) ) ) ( , ( ( water vapor ) ( ( ( condenses , ) ( forming ( the cloud ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN As) (S (NP (DT the) (NN air)) (VP (VBZ is) (VP (VBN lifted))))) (, ,) (NP (NN water) (NN vapor)) (VP (VBZ condenses) (, ,) (S (VP (VBG forming) (NP (DT the) (NN cloud))))) (. .)))
As the air is lifted, water vapor condenses, forming the cloud.
(ROOT (S (NP (NNP Water) (NN vapor)) (VP (MD must) (VP (VB lose) (NP (NN heat) (NN energy)) (SBAR (IN before) (S (NP (NNS clouds)) (VP (MD can) (VP (VB form))))))) (. .)))
Water vapor must lose heat energy before clouds can form.