( ( Hot spots ) ( generally ( ( form ( ( ( because ( of ( variations ( in ( the ( wind ( and ( weather patterns ) ) ) ) ) ) ) ) and ) ( in ( ( ( the ( earth 's ) ) surface ) ( -LRB- ( ( such ( as ( ( ( hills and ) valleys ) ( that ( cause ( air pockets ) ) ) ) ) ) -RRB- ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (JJ Hot) (NNS spots)) (ADVP (RB generally)) (VP (VBP form) (PP (PP (RB because) (IN of) (NP (NP (NNS variations)) (PP (IN in) (NP (DT the) (NN wind) (CC and) (NN weather) (NNS patterns))))) (CC and) (PP (IN in) (NP (NP (NP (DT the) (NN earth) (POS 's)) (NN surface)) (PRN (-LRB- -LRB-) (PP (JJ such) (IN as) (NP (NP (NNS hills) (CC and) (NNS valleys)) (SBAR (WHNP (WDT that)) (S (VP (VBP cause) (NP (NN air) (NNS pockets))))))) (-RRB- -RRB-)))))) (. .)))
Hot spots generally form because of variations in the wind and weather patterns and in the earth's surface (such as  hills and valleys that cause air pockets).
(ROOT (S (NP (NP (DT The) (NN movement)) (PP (IN of) (NP (NP (DT an) (NN air) (NN mass)) (PP (IN over) (NP (NP (NN earth) (POS 's)) (NN surface)))))) (VP (VBZ causes) (NP (JJ local) (NN weather) (NNS changes))) (. .)))