( Dispersion ( ( is ( controlled ( ( ( by ( ( ( diffusion , ) ( which ( is ( ( the movement ) ( from ( areas ( of ( ( high ( to low ) ) concentrations ) ) ) ) ) ) ) ) , ) ) and ) ( by ( ( mixing , ) ( which ( is ( ( the movement ) ( of ( air ( in ( the space ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Dispersion)) (VP (VBZ is) (VP (VBN controlled) (PP (PP (IN by) (NP (NP (NN diffusion)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (DT the) (NN movement)) (PP (IN from) (NP (NP (NNS areas)) (PP (IN of) (NP (ADJP (JJ high) (TO to) (JJ low)) (NNS concentrations))))))))) (, ,))) (CC and) (PP (IN by) (NP (NP (NNP mixing)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (DT the) (NN movement)) (PP (IN of) (NP (NP (NN air)) (PP (IN in) (NP (DT the) (NN space)))))))))))))) (. .)))
Dispersion is controlled by diffusion, which is the movement from areas of high to low concentrations, and by mixing, which is the movement of air in the space.
(ROOT (S (NP (NNP Diffusion)) (VP (VBZ is) (NP (NP (DT the) (NN process)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (DT a) (NN substance)) (ADVP (RB naturally)) (VP (VBZ moves) (PP (IN from) (NP (NP (DT an) (NN area)) (PP (IN of) (NP (NP (JJR higher)) (PP (TO to) (NP (JJR lower) (NN concentration)))))))))))) (. .)))
Diffusion is the process in which a substance naturally moves from an area of higher to lower concentration.