( ( Once aloft ) ( , ( ( the dust ) ( ( ( is ( very likely ) ) ( to ( ( stay aloft ) ( until ( it ( ( meets water ) ( in ( ( ( ( the form ) ( of rain ) ) or ) ( ( a body ) ( of water ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Once) (FRAG (ADVP (RB aloft)))) (, ,) (NP (DT the) (NN dust)) (VP (VBZ is) (ADJP (RB very) (JJ likely)) (S (VP (TO to) (VP (VB stay) (ADVP (RB aloft)) (SBAR (IN until) (S (NP (PRP it)) (VP (VBZ meets) (NP (NN water)) (PP (IN in) (NP (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NN rain)))) (CC or) (NP (NP (DT a) (NN body)) (PP (IN of) (NP (NN water))))))))))))) (. .)))
Once aloft, the dust is very likely to stay aloft until it meets water in the form of rain or a body of water.
(ROOT (S (NP (NNP Birds)) (VP (VBP need) (NP (DT a) (JJ light-weight) (NN body)) (PP (IN for)) (S (VP (TO to) (VP (VB stay) (ADVP (RB aloft)))))) (. .)))