( Conditions ( ( tend ( to ( ( follow ( a ( 27 ( day cycle ) ) ) ) ( because ( ( the sun ) ( ( rotates ( on ( its axis ) ) ) ( once ( every ( 27 ( earth days ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Conditions)) (VP (VBP tend) (S (VP (TO to) (VP (VB follow) (NP (DT a) (CD 27) (NN day) (NN cycle)) (SBAR (IN because) (S (NP (DT the) (NN sun)) (VP (VBZ rotates) (PP (IN on) (NP (PRP$ its) (NNS axis))) (PP (RB once) (NP (DT every) (CD 27) (NN earth) (NNS days)))))))))) (. .)))
Conditions tend to follow a 27 day cycle because the sun rotates on its axis once every 27 earth days.
(ROOT (S (NP (NNP Earth)) (VP (VBZ rotates) (PP (PP (IN on) (NP (PRP$ its) (NNS axis)) (ADVP (RB once))) (CC times) (PP (IN in) (NP (CD one) (NN day))))) (. .)))