( Evaporation ( ( is ( when ( water ( ( changes ( from ( its ( liquid state ) ) ) ) ( into ( a vapor ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Evaporation)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (NN water)) (VP (VBZ changes) (PP (IN from) (NP (PRP$ its) (JJ liquid) (NN state))) (PP (IN into) (NP (DT a) (NN vapor))))))) (. .)))
Evaporation is when water changes from its liquid state into a vapor.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (JJ liquid) (NN water) (NNS changes)) (VP (TO to) (VP (VB water) (NP (NN vapor)))))) (NP (PRP it)) (VP (VBZ is) (VP (VBN called) (NP (NN evaporation)))) (. .)))
When liquid water changes to water vapor it is called evaporation.