( Clouds ( ( ( ( formed ( by ( condensation ( of ( water vapor ) ) ) ) ) , ) ( affect weather ) ) . ) )
(ROOT (S (NP (NNS Clouds)) (VP (VBD formed) (PP (IN by) (NP (NP (NN condensation)) (PP (IN of) (NP (NN water) (NN vapor))))) (, ,) (S (VP (VB affect) (NP (NN weather))))) (. .)))
Clouds formed by condensation of water vapor, affect weather.
(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.