( Evaporation ( ( occurs ( when ( ( water ( on ( the surface ) ) ) ( changes ( to ( water vapor ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Evaporation)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NP (NN water)) (PP (IN on) (NP (DT the) (NN surface)))) (VP (VBZ changes) (PP (TO to) (NP (NN water) (NN vapor))))))) (. .)))
Evaporation occurs when water on the surface changes to water vapor.
(ROOT (S (NP (NNP Evaporation)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NP (NN water)) (PP (IN on) (NP (DT the) (NN surface)))) (VP (VBZ changes) (PP (TO to) (NP (NN water) (NN vapor))))))) (. .)))