( ( Influence ( of ( nitric acid ) ) ) ( ( vapor ( on ( ( cloud ( particle formation ) ) ( at ( ( low temperatures ) ( in troposphere ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Influence)) (PP (IN of) (NP (JJ nitric) (NN acid)))) (VP (VBP vapor) (PP (IN on) (NP (NP (NN cloud) (NN particle) (NN formation)) (PP (IN at) (NP (NP (JJ low) (NNS temperatures)) (PP (IN in) (NP (NNP troposphere)))))))) (. .)))
Influence of nitric acid vapor on cloud particle formation at low temperatures in troposphere.
(ROOT (S (NP (NNP Stratus) (NNS clouds)) (VP (VBP occur) (PP (IN in) (NP (NP (DT the) (NN low)) (PP (IN of) (NP (DT the) (NNP troposphere)))))) (. .)))