( ( Most ( likely ( in ( freezing rain ) ) ) ) ( ( since ( drops ( ( ( ( form ( continuous ( heavy sheet ) ) ) ( as ( they ( spread out ) ) ) ) and ) freeze ) ) ) . ) )
(ROOT (FRAG (ADJP (RBS Most) (JJ likely) (PP (IN in) (NP (JJ freezing) (NN rain)))) (SBAR (IN since) (S (NP (NNS drops)) (VP (VP (VB form) (NP (JJ continuous) (JJ heavy) (NN sheet)) (SBAR (IN as) (S (NP (PRP they)) (VP (VBD spread) (PRT (RP out)))))) (CC and) (VP (VB freeze))))) (. .)))
Most likely in freezing rain since drops form continuous heavy sheet as they spread out and freeze.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (NP (DT the) (NN earth) (POS 's)) (NN freshwater)))) (VP (VBZ is) (PP (IN in) (NP (NP (DT the) (NN form)) (PP (IN of) (ADJP (JJ frozen)))))) (. .)))