( 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 Condensation)) (VP (MD must) (VP (VB occur) (PP (IN for) (NP (NNS clouds))) (S (VP (TO to) (VP (VB form)))))) (. .)))