( ( ( These ( meteors collide ) ) ( with ( ( the molecules ) ( of ( air ( in ( ( ( our atmosphere ) and ) ( the ( resulting friction ) ) ) ) ) ) ) ) ) ( ( causes ( them ( to ( burn up ) ) ) ) . ) )
(ROOT (S (NP (NP (DT These) (JJ meteors) (NN collide)) (PP (IN with) (NP (NP (DT the) (NNS molecules)) (PP (IN of) (NP (NP (NN air)) (PP (IN in) (NP (NP (PRP$ our) (NN atmosphere)) (CC and) (NP (DT the) (VBG resulting) (NN friction))))))))) (VP (VBZ causes) (S (NP (PRP them)) (VP (TO to) (VP (VB burn) (PRT (RP up)))))) (. .)))
These meteors collide with the molecules of air in our atmosphere and the resulting friction causes them to burn up.
(ROOT (S (NP (NN Friction) (NN force)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (JJ microscopic) (NNS bumps)) (, ,) (VP (VBZ lumps)) (, ,) (CC and) (NP (NP (NNS imperfections)) (VP (VBG colliding))))))) (. .)))