( ( As ( water ( vapor rises ) ) ) ( , ( it ( ( ( ( becomes cooler ) , ) ( ( ( losing energy ) and ) ( forming clouds ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (NN water) (NN vapor) (NNS rises))) (, ,) (NP (PRP it)) (VP (VBZ becomes) (NP (JJR cooler)) (, ,) (S (VP (VP (VBG losing) (NP (NN energy))) (CC and) (VP (VBG forming) (NP (NNS clouds)))))) (. .)))
As water vapor rises, it becomes cooler, losing energy and forming 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.