( ( ( Small particles ) ( in ( the air ) ) ) ( ( become ( surfaces ( ( on which ) ( ( water vapor ) ( ( ( can condense ) and ) ( forms ( ( cloud droplets ) ( which ( are ( known ( as ( cloud ( condensation nuclei ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Small) (NNS particles)) (PP (IN in) (NP (DT the) (NN air)))) (VP (VBP become) (NP (NP (NNS surfaces)) (SBAR (WHPP (IN on) (WHNP (WDT which))) (S (NP (NN water) (NN vapor)) (VP (VP (MD can) (VP (VB condense))) (CC and) (VP (VBZ forms) (NP (NP (NN cloud) (NNS droplets)) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (VP (VBN known) (PP (IN as) (NP (NN cloud) (NN condensation) (NNS nuclei)))))))))))))) (. .)))
Small particles in the air become surfaces on which water vapor can condense and forms cloud droplets which are known as cloud condensation nuclei.
(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)))))))))))) (. .)))