( ( ( The change ) ( in ( gravity ( ( caused ( by ( ( a change ) ( in ( ( the distance ) ( of ( ( a point ) ( on ( ( the surface ) ( of ( the Earth ) ) ) ) ) ) ) ) ) ) ) ( from ( ( the center ) ( of ( the mass ) ) ) ) ) ) ) ) ( ( is ( ( ( approximately 3 ) microgal ) ( per centimeter ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN change)) (PP (IN in) (NP (NP (NN gravity)) (VP (VBN caused) (PP (IN by) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NP (DT the) (NN distance)) (PP (IN of) (NP (NP (DT a) (NN point)) (PP (IN on) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (DT the) (NN Earth))))))))))) (PP (IN from) (NP (NP (DT the) (NN center)) (PP (IN of) (NP (DT the) (NN mass))))))))) (VP (VBZ is) (NP (NP (QP (RB approximately) (CD 3)) (NN microgal)) (PP (IN per) (NP (NN centimeter))))) (. .)))
The change in gravity caused by a change in the distance of a point on the surface of the Earth from the center of the mass is approximately 3 microgal per centimeter.
(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))) (. .)))