Umkhenkce kunye nobudala bomkhenkce

Kuzo zonke izigidi zeminyaka ezidlulileyo ukusukela oko uMhlaba wasekwayo, kuye kwakho amaxesha exesha lomkhenkce. Babizwa ngokuba imiyaka yomkence. La ngamaxesha ngamaxesha apho utshintsho lwemozulu lwenzeka kumaqondo obushushu asezantsi ehlabathi. Benza ngendlela yokuba uninzi lomhlaba womkhenkce ungaphezulu. Kubalulekile ukuba wazi ukuba xa uthetha ngotshintsho lwemozulu kufuneka ubenesiqulatho sokuzibeka kwimeko yeplanethi yethu.

Ngaba uyafuna ukwazi iinkqubo ze-glaciation kunye ne-ice Age yethu? Apha sityhila yonke into.

Iimpawu zexesha lomkhenkce

Ubudala beqhwa buchazwa njengexesha lexesha elibonakaliswa bubukho obungapheliyo bekhava yomkhenkce. Lo mkhenkce udlulela kwesinye sezibonda. Umhlaba uyaziwa ukuba udlulile I-90% yexesha layo ngexesha lesigidi sokugqibela kwi-1% yamaqondo obushushu abanda kakhulu. La maqondo obushushu asezantsi ukusukela kwiminyaka eyi-500 yezigidi edlulileyo. Ngamanye amagama, uMhlaba ubanjwe kwindawo ebanda kakhulu. Eli xesha laziwa njengeQuaternary Ice Age.

Iminyaka emine yokugqibela yeqhwa yenzekile kunye Ixesha lekhefu eliyizigidi ezili-150. Ke ngoko, izazinzulu zicinga ukuba zibangelwe lutshintsho kumjikelezo woMhlaba okanye utshintsho kwimisebenzi yelanga. Ezinye izazinzulu zikhetha inkcazo yomhlaba. Umzekelo, ukubonakala kwexesha lomkhenkce kubhekisele kusasazo lwamazwekazi okanye uxinzelelo lweegesi zegreenhouse.

Ngokwenkcazo ye-glaciation, lixesha elibonakaliswa bubukho bemikhenkce kwiipali. Ngalo mthetho wobhontsi, sitshona nje kwisigaba somkhenkce, kuba ii-polar caps zihlala phantse i-10% yomhlaba wonke.

I-Glaciation iqondwa njengethuba lamaxesha omkhenkce apho amaqondo obushushu asezantsi kakhulu kwihlabathi liphela. Imikhenkce, ngenxa yoko, iya kwinqanaba eliphantsi kwaye ilawula amazwekazi. Iminqwazi yomkhenkce ifunyenwe kububanzi beikhweyitha. Ixesha lokugqibela lomkhenkce lenzeka malunga ne-11 lamawaka eminyaka eyadlulayo.

Iminyaka eyaziwayo yomkhenkce

Kukho isebe lesayensi elinoxanduva lokufunda ngomkhenkce. Imalunga ne-glaciology. Nguye ophetheyo ekufundeni konke ukubonakaliswa kwendalo kwamanzi kwimeko eqinileyo. Ngamanzi akwimo eqinileyo babhekisa kwiikhephu, ikhephu, isichotho, i-sleet, umkhenkce kunye nolunye ulwakhiwo.

Ixesha ngalinye le-glaciation lahlulwe laba yimizuzu emibini: glacial kunye interglacial. Ezangaphambili zezo zezo apho imeko yokusingqongileyo igqithile kwaye iqabaka livela phantse kuyo yonke indawo emhlabeni. Kwelinye icala, ii-interglaciers zinobushushu ngakumbi, njengoko zinjalo namhlanje.

Ukuza kuthi ga ngoku, amaxesha amahlanu obudala beqhwa aziwa kwaye aqinisekisiwe: Quaternary, Karoo, Andean-Saharan, Cryogenic kunye neHuronia. Zonke ezi zinto zenzekile ukusukela ngexesha lokusekwa komhlaba.

Iminyaka ye-Ice ayibonakaliswanga kuphela ngamaconsi abukhali kubushushu, kodwa nangokunyuka ngokukhawuleza.

Ixesha le-Quaternary laqala kwiminyaka ezi-2,58 yezigidi eyadlulayo kwaye lihlala unanamhla. I-Karoo, ekwabizwa ngokuba lixesha le-Permo-Carboniferous, yayiyeyona inde, yayihlala malunga ne-100 lezigidi zeminyaka, phakathi kwe-360 kunye ne-260 yezigidi zeminyaka eyadlulayo.

Kwelinye icala, ixesha lomkhenkce laseAndean-Sahara liye lahlala kuphela kwizigidi ezingama-30 zeminyaka kwaye lenzeka phakathi kweminyaka engama-450 nengama-430 eyadlulayo. Elona xesha ligqithisileyo elenzekayo kwiplanethi yethu ngokungathandabuzekiyo li-cryogenic. Yeyona minyaka inzima yomkhenkce kuyo yonke imbali yejoloji yeplanethi. Kweli nqanaba kuqikelelwa ukuba umkhenkce owawugubungele amazwekazi wafikelela kwiikhweyitha.

I-Huronian glaciation yaqala kwiminyaka ezi-2400 yezigidi eyadlulayo kwaye yaphela malunga nama-2100 eyadlulayo.

Ixesha lokugqibela lomkhenkce

Okwangoku sikwixesha lokuhlangana phakathi kwe-Quaternary glaciation. Indawo engaphezulu egcinwe yiminqwazi ye-polar ifikelela kwi-10% yomhlaba wonke. Ubungqina busixelela ukuba phakathi kwesi sithuba se-quaternary, kukho amaxesha amaninzi e-ice.

Xa abantu bebhekisa kwi "Ice Age" ibhekisa kwixesha lokugqibela lomkhenkce elixesha lokuzalwa. Kwaqala ikota yokuqala Iminyaka engama-21000 eyadlulayo kwaye yaphela malunga neminyaka engama-11500 XNUMX eyadlulayo. Kwenzeke ngaxeshanye kuzo zombini iihemispheres. Elona likhulu likhulu lomkhenkce lafikelelwa kumantla eikhweyitha. EYurophu, umkhenkce waqhubela phambili, wagubungela iGreat Britain, iJamani nePoland. Yonke iNyakatho Melika yangcwatywa phantsi komkhenkce.

Emva kwengqele, ulwandle lwehla nge-120 leemitha. Ububanzi obukhulu bolwandle namhlanje babenzelwe elo xesha emhlabeni. Le datha ibaluleke kakhulu xa kufundwa uguquko lwemfuza kubemi abaninzi bezilwanyana nezityalo. Ngexesha lokuhamba kwabo kwiindawo zomhlaba ngexesha lomkhenkce, babekwazi ukutshintshiselana ngemfuza kwaye bafudukele kwamanye amazwekazi.

Ngombulelo kumgangatho ophantsi wolwandle, sikwazile ukuhamba ngeenyawo ukusuka eSiberia ukuya eAlaska. Uninzi olukhulu lomkhenkce bafikelela kubunzima beemitha ezingama-3.500 4.000 ukuya kuma-XNUMX, egubungela isinye kwisithathu samazwe avelileyo.

Namhlanje, kuqikelelwe ukuba xa umkhenkce oshiyekileyo unyibilikile, amanqanaba elwandle angenyuka phakathi kwe-60 kunye ne-70 yeemitha.

Oonobangela glaciation

Ukuqhubela phambili nokubuyela umva komkhenkce kunxulumene nokupholisa uMhlaba. Oku kungenxa yotshintsho kwifayile ye- ukwakhiwa komoya kunye notshintsho kumjikelezo woMhlaba ojikeleze iLanga. Isenokubangelwa lutshintsho kumjikelezo weLanga kumnyele wethu, iMilky Way.

Abo bacinga ukuba ukuqhwaqeka komhlaba kubangelwa zizizathu zangaphakathi zomhlaba bakholelwa ukuba zibangelwe ngamandla eeplate zeetectonic kunye nefuthe labo kwimeko enxulumene noko kunye nenani lolwandle nolwandle emhlabeni. Abanye bakholelwa ukuba kungenxa yotshintsho kwimisebenzi yelanga okanye amandla e-Earth-Moon orbit.

Okokugqibela, kukho ithiyori edibanisa ifuthe leemeteorites okanye zokuqhuma kwentaba-mlilo enkulu kunye ne-glaciation.

Oonobangela bahlala bevelisa impikiswano kwaye izazinzulu zithi sikufutshane ekupheliseni eli xesha lokuhlangana. Ngaba ucinga ukuba kuya kubakho ixesha elitsha lomkhenkce kungekudala?