( ( In ( ( order ( for rain ) ) ( to fall ) ) ) ( , ( ( ice crystals ) ( ( must ( form ( in ( ( the ( water vapor ) ) ( in clouds ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NP (NN order)) (PP (IN for) (NP (NN rain))) (S (VP (TO to) (VP (VB fall)))))) (, ,) (NP (NN ice) (NNS crystals)) (VP (MD must) (VP (VB form) (PP (IN in) (NP (NP (DT the) (NN water) (NN vapor)) (PP (IN in) (NP (NNS clouds))))))) (. .)))
In order for rain to fall, ice crystals must form in the water vapor in clouds.
(ROOT (S (NP (NNP Water) (NN vapor)) (VP (MD must) (VP (VB lose) (NP (NN heat) (NN energy)) (SBAR (IN before) (S (NP (NNS clouds)) (VP (MD can) (VP (VB form))))))) (. .)))
Water vapor must lose heat energy before clouds can form.