( Clouds ( ( form ( when ( ( ( the ( invisible ( water vapor ) ) ) ( in ( the air ) ) ) ( condenses ( into ( visible ( water ( droplets ( or ( ice crystals ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Clouds)) (VP (VBP form) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT the) (JJ invisible) (NN water) (NN vapor)) (PP (IN in) (NP (DT the) (NN air)))) (VP (VBZ condenses) (PP (IN into) (NP (JJ visible) (NN water) (NNS droplets) (CC or) (NN ice) (NNS crystals))))))) (. .)))
Clouds form when the invisible water vapor in the air condenses into visible water droplets or ice crystals.
(ROOT (S (VP (VB Clouds) (NP (NP (NN form)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-)) (SBAR (WHADVP (WRB when)) (S (NP (NN water) (NN vapor)) (VP (VBZ condenses) (PP (IN in) (NP (NP (DT the) (NN air)) (PP (IN around) (NP (NP (NNS specs)) (PP (IN of) (NP (NN matter)))))))))))) (. .)))