( Frost ( ( describes ( ( the formation ) ( of ( ( ( ( thin ( ice crystals ) ) ( on ( the ground ) ) ) or ) ( ( other surfaces ) ( in ( ( the form ) ( of ( scales ( , ( needles ( , ( feathers ( , ( or fans ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Frost)) (VP (VBZ describes) (NP (NP (DT the) (NN formation)) (PP (IN of) (NP (NP (NP (JJ thin) (NN ice) (NNS crystals)) (PP (IN on) (NP (DT the) (NN ground)))) (CC or) (NP (NP (JJ other) (NNS surfaces)) (PP (IN in) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NNS scales) (, ,) (NNS needles) (, ,) (NNS feathers) (, ,) (CC or) (NNS fans)))))))))) (. .)))
Frost describes the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans.
(ROOT (S (NP (NP (DT The) (NN ice) (NNS crystals)) (SBAR (WHNP (WDT that)) (S (VP (VBP form) (PP (IN on) (NP (DT the) (NN ground))))))) (VP (VBP are) (VP (VBN called) (S (ADJP (JJ frost))))) (. .)))