ill ages ▁in ▁Champ aign ▁County , ▁Illinois <0x0A> </s> ▁Cy c log en esis ▁is ▁the ▁development ▁or ▁strength ening ▁of ▁cycl onic ▁circul ation ▁in ▁the ▁atmosphere ▁( a ▁low - press ure ▁area ). ▁Cy c log en esis ▁is ▁an ▁um bre lla ▁term ▁for ▁at ▁least ▁three ▁different ▁processes , ▁all ▁of ▁which ▁result ▁in ▁the ▁development ▁of ▁some ▁sort ▁of ▁cy clone , ▁and ▁at ▁any ▁size ▁from ▁the ▁micro scale ▁to ▁the ▁syn opt ic ▁scale . ▁▁ ▁Trop ical ▁cycl ones ▁form ▁due ▁to ▁lat ent ▁heat ▁driven ▁by ▁significant ▁th under st orm ▁activity , ▁developing ▁a ▁warm ▁core . ▁ ▁Ext rat rop ical ▁cycl ones ▁form ▁as ▁waves ▁along ▁weather ▁front s ▁before ▁occ l ud ing ▁later ▁in ▁their ▁life ▁cycle ▁as ▁cold ▁core ▁cycl ones . ▁ ▁Mes ocy cl ones ▁form ▁as ▁warm ▁core ▁cycl ones ▁over ▁land , ▁and ▁can ▁lead ▁to ▁torn ado ▁formation . ▁W aters p outs ▁can ▁also ▁form ▁from ▁mes ocy cl ones , ▁but ▁more ▁often ▁develop ▁from ▁environments ▁of ▁high ▁inst ability ▁and ▁low ▁vertical ▁wind ▁she ar . ▁ ▁The ▁process ▁in ▁which ▁an ▁extr at rop ical ▁cy clone ▁under go es ▁a ▁rapid ▁drop ▁in ▁atmos pher ic ▁pressure ▁( 2 4 ▁mill ib ars ▁or ▁more ) ▁in ▁a ▁ 2 4 - hour ▁period ▁is ▁referred ▁to ▁as ▁explos ive ▁cy c log en esis , ▁and ▁is ▁usually ▁present ▁during ▁the ▁formation ▁of ▁a ▁nor