( ( ( ( ( Solar cycle ) ( -LRB- ( or ( ( sunspot cycle ) -RRB- ) ) ) ) -- ) ( ( ( an ( irregular cycle ) ) , ) ( ( averaging ( ( about 11 ) years ) ) ( in ( ( length , ) ( ( during which ) ( ( ( the number ) ( of ( sunspots ( -LRB- ( ( and ( of ( their ( associated outbursts ) ) ) ) -RRB- ) ) ) ) ) ( ( rises and ) ( then ( drops again ) ) ) ) ) ) ) ) ) ) . )
(ROOT (NP (NP (NNP Solar) (NN cycle)) (PRN (-LRB- -LRB-) (CC or) (NP (NP (NN sunspot)) (NP (NN cycle))) (-RRB- -RRB-)) (: --) (NP (NP (DT an) (NN irregular) (NN cycle)) (, ,) (VP (VBG averaging) (NP (QP (RB about) (CD 11)) (NNS years)) (PP (IN in) (NP (NP (NN length)) (, ,) (SBAR (WHPP (IN during) (WHNP (WDT which))) (S (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS sunspots)) (PRN (-LRB- -LRB-) (FRAG (CC and) (PP (IN of) (NP (PRP$ their) (JJ associated) (NNS outbursts)))) (-RRB- -RRB-))))) (VP (VP (VBZ rises)) (CC and) (VP (ADVP (RB then)) (VBZ drops) (ADVP (RB again)))))))))) (. .)))
Solar cycle (or sunspot cycle)--an irregular cycle, averaging about 11 years in length, during which the number of sunspots (and of their associated outbursts) rises and then drops again.
(ROOT (S (NP (NNS Sunspots)) (VP (VBP occur) (PP (IN in) (NP (DT a) (CD 11) (NN year) (NN cycle)))) (. .)))