( ( ( A. 1 ) ( I21 ( ( The ( primary cause ) ) ( of ( ( all changes ) ( in ( ( the ( Earth 's ) ) weather ) ) ) ) ) ) ) ( ( is ( ( A. movement ) ( of ( the ( air masses ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP A.) (CD 1)) (VP (VBG I21) (NP (NP (DT The) (JJ primary) (NN cause)) (PP (IN of) (NP (NP (DT all) (NNS changes)) (PP (IN in) (NP (NP (DT the) (NN Earth) (POS 's)) (NN weather)))))))) (VP (VBZ is) (NP (NP (NN A.) (NN movement)) (PP (IN of) (NP (DT the) (NN air) (NNS masses))))) (. .)))
A.1 I21 The primary cause of all changes in the Earth's weather is A. movement of the air masses.
(ROOT (S (NP (NP (DT The) (NN movement)) (PP (IN of) (NP (NP (DT an) (NN air) (NN mass)) (PP (IN over) (NP (NP (NN earth) (POS 's)) (NN surface)))))) (VP (VBZ causes) (NP (JJ local) (NN weather) (NNS changes))) (. .)))