( ( ( ( Clouds ( form ( when ( condensation ( takes place ) ) ) ) ) but ) ( condensation ( forms ( ( tiny ( water droplets ) ) ( that ( condense ( on ( ( minute ( dust particles ) ) ( in ( the air ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNS Clouds)) (VP (VBP form) (SBAR (WHADVP (WRB when)) (S (NP (NN condensation)) (VP (VBZ takes) (NP (NN place))))))) (CC but) (S (NP (NN condensation)) (VP (VBZ forms) (NP (NP (JJ tiny) (NN water) (NNS droplets)) (SBAR (WHNP (WDT that)) (S (VP (VBP condense) (PP (IN on) (NP (NP (JJ minute) (NN dust) (NNS particles)) (PP (IN in) (NP (DT the) (NN air))))))))))) (. .)))
Clouds form when condensation takes place but condensation forms tiny water droplets that condense on minute dust particles in the air.
(ROOT (S (NP (NNP Condensation)) (VP (MD must) (VP (VB occur) (PP (IN for) (NP (NNS clouds))) (S (VP (TO to) (VP (VB form)))))) (. .)))