Kwiplanethi yethu kunezixuku ezinkulu zeqhwa ezisibekela izingongolo ezisenyakatho naseningizimu. Leli qhwa alikho olwandle kuphela kodwa futhi litholakala nasezintabeni. Lezi zingqimba zeqhwa zaziwa njenge izinguzunga zeqhwa. Lapho lezi zinguzunga zeqhwa zifinyelela ubukhulu obukhulu kangangokuba zivame ukumboza izindawo eziphelele nezinabanzi, ziyabizwa izimbotshana zeqhwa elisendaweni emincane.
Kulesi sihloko sizokutshela zonke izici, ukubaluleka, amandla alezi zinhlayiya ezisezindaweni ezibandayo nokuthi kuzokwenzekani uma zonke lezi zigaxa zeqhwa zigcina zincibilikile.
Ukwakheka kwezinguzunga zeqhwa
Ukwenza indlela yamakhemikhali asezindaweni ezibandayo, okokuqala kudingekile ukwazi ukuthi izingqimba zeqhwa zakhiwa kanjani ukuze zisabalale ngendlela yokuthi ekugcineni zakhe isicoco se-polar. Konke ukumbozwa kweqhwa okusabalale ngesikhathi sokugcina i-glaciation noma i-ice age yakha izinguzunga zeqhwa. Lezi zinguzunga zeqhwa zibaluleke kakhulu njengama-erosive agents kanye nabakhi bokusiza, inhlabathi nezwe.
Esinye isizathu sokuthi kungani zibalulekile yingoba zingumthombo omkhulu wamanzi ahlanzekile emhlabeni. Kunezinto eziningi eziphilayo ezisizakala ngamanzi ancibilikile ehlobo lamaqhwa eqhwa ukuze ziqhubeke ziphila, zizalane noma zenze indawo yazo yemvelo yokuhlala.
Lezi zinguzunga zeqhwa zakhiwa ngokuqongelela, unyaka nonyaka, iqhwa eliwela ngaphansi nasemithambekeni yezigodi. Zitholakala ezindaweni eziphakeme zezintaba. Ubukhulu bungafinyelela ingxenye enkulu uma iqhwa elilahlekile ngenxa yokuncibilika ehlobo lingaphansi kwalelo eliqongelela ngenkathi yeqhwa.
Isisindo esihlanganisiwe saleli qhwa senziwa ngoba ukuwa ngakunye kweqhwa kucindezelwa kuleso ebesifakwe ngaphambilini phambilini. Uma ukushisa kokuncibilika kuphumelela ekuncibilikiseni iqhwa, kuzolibangela ukuthi likhuluphale bese liqala ukuya phansi kwesigodi.
Ukuminyana kwesithwathwa kuvame ukukhuphuka ngokujula njengoba kunenani elikhulu leqhwa ngeyunithi ngayinye yendawo, okulenza liminyene. Leli phunga abanalo liyisisekelo seqhwa futhi ligeleza sengathi uketshezi. Ngaphakathi kweqhwa, iqhwa lihamba ngokushesha kakhulu kunezindawo ezisemaceleni, yingakho ukuphuka, ukungezwani, nokunwebeka kuvame ukwenzeka, okubangela ukuba kuvele izimfantu phezulu. Lezi zinqubo, kanye nomthelela we- ukushintsha kwesimo sezulu, kuthinta ukuguquguquka kwezinguzunga zeqhwa nokuthuthuka kwazo.
Amandla we-Glacial
Inguzunga yeqhwa iyahamba futhi isiphule amatshe ayizilinganiso ezisendleleni yawo. Izingcezu zamatshe ezibangelwa yilokhu kuhamba kwezinguzunga zeqhwa zaziwa ngokuthi ama-moraines. Indawo esekupheleni kweqhwa kulapho incibilikisi yakhiwa khona. Lapha, ungabona ukwakheka kwamagquma amancane abizwa nge-terminal moraine.
Uma nje i-glacier igcina indawo ephezulu yokunqwabelana kweqhwa ngenxa yemvula, umjikelezo weqhwa uzohlala uphila. Ekugcineni, endaweni ephansi kakhulu, iqhwa liyancibilika, kwakheka imifudlana yamanzi ahlanzekile. Kubalulekile ukuqaphela ukuthi i- ukufudumala kwezwe isheshisa le nqubo yokuncibilika ezifundeni eziningi.
Kukhona izinguzunga zeqhwa ezigeleza ezigodini phansi kohlelo lwezintaba. Lapho zihlangana zakha i-glacier enkulu yaziwa njenge-piedmont.
Ama-polar caps kanye ne-ice cap
Uma sesizwisisile ukuthi iyini iqhwa, ukuthi yakha kanjani, nokuthi iyini i-dynamics yayo, siqhubekela phambili ekuchazeni izingqimba zeqhwa. Uma iqhwa elishiwo ngenhla limboza amathafa neziqhingi ezindaweni eziphakeme neziphansi, laziwa ngokuthi iqhwa elisezindaweni ezishisayo. Lezi zinguzunga zeqhwa ngokuvamile zizalelwa ezindaweni zeqhwa ze-alpine futhi zehla ezigodini. Ekugcineni, bafinyelela olwandle ngezikhathi ezithile.
Uma iqhwa libanzi kangangokuthi limboza lonke izwekazi, libizwa ngokuthi i-continental ice sheet. Lokhu kwenzeka ngamaqhwa eqhwa ase-Arctic nase-Antarctica. Lolu ngqimba olukhulu lweqhwa lugeleza luye ngaphandle luze lufike olwandle, lapho luhlukana khona lube ngamasayizi ahlukahlukene, lwenze izinguzunga zeqhwa. Ukuziphendukela kwemvelo kwala ma-icebergs nakho kuthonywa yi- Ukukhuphuka kwamazinga olwandle ngenxa yokuncibilika.
Igama elithi polar caps lisetshenziselwa ukuchaza izinhlobonhlobo zeqhwa ezitholakala e-Antarctica naseGreenland. Ngakho-ke, noma nini lapho sikhuluma ngokufudumala komhlaba noma ngokushintsha kwesimo sezulu sikhuluma ngokuncibilika kwamakhekheba eqhwa asezindaweni ezibandayo. Lezi zinhlayiya ezisezindaweni eziphakeme kuzo zombili izingongolo zakhiwa ngesikhathi seqhwa lasePleistocene, esikhathini seQuaternary futhi zafika zamboza ingxenye enkulu yesifunda esisenyakatho.
Isigqoko se-polar saziwa njengesembatho seqhwa futhi imvamisa sinokwandiswa kwe- ngaphezu kwamakhilomitha-skwele ayizigidi eziyi-1,8 ebusweni. Ngokuya ngobukhulu, zikumamitha ayi-2.700 ubuningi. Lezi zindwangu ezisemaphandleni zimboza ingxenye enkulu yobuso baseGreenland. Idwala lesisekelo livela kuphela eduze nogu lapho inguzunga yeqhwa ingenamandla ngokwanele futhi izingcezu zakhe izilimi zeqhwa. Lapho izilimi zifinyelela olwandle, ziqhekeka ziqhubeke zibe izingcezu zeqhwa phakathi nenkathi yokuncibilika, zakhe izinguzunga zeqhwa.
Ama-Icebergs anamandla awo futhi ayanyamalala ngokuhamba kweminyaka. Isembozo se-polar salokhu okunamandla simboza i-Antarctica, kuphela lesi siqhwa inendawo engamakhilomitha-skwele ayizigidi eziyi-13.
Kuzokwenzekani uma izingqimba zeqhwa zincibilika?
Ngokuguquka kwesimo sezulu nokwanda komphumela wokushisa okushisayo, kukhulunywa ngokuncibilika kwamakhekheba eqhwa asezindaweni ezibandayo. Umphumela walokhu ukuthi ulwandle luzonyuka. Cabanga ukuthi izingqimba zeqhwa zigxila cishe ku-70% wawo wonke amanzi ahlanzekile emhlabeni. Uma la manzi, lokho okusemhlabeni kugcina kuncibilikile, kuzophelela olwandle.
Ososayensi balinganisela ukuthi ngonyaka ka-2100, ulwandle luzobe selukhuphuke ngesilinganiso samasentimitha angama-50 ukusuka olwandle. Lokhu kusho ukuthi amadolobha amaningi asogwini azothinteka kabi futhi ezinye izinhlelo eziningi zemvelo kuzodingeka zivumelane futhi. Ngaphezu kwalokho, i- i-albedo yomhlaba izophinde ithinteke ngoba kunendawo encane emhlophe ekhombisa izehlakalo zemisebe yelanga.
Ubudlelwano phakathi kokuncibilika kanye ukushintsha kwesimo sezulu kubalulekile, futhi imiphumela yokuncibilika kwezingqimba zeqhwa iyinkimbinkimbi futhi inezici eziningi.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngamakhanda we-polar nemiphumela yokuncibilika kwawo.