Izinguzunga zeqhwa yizinkumbi zeqhwa ezicindezelwe ezakha ngaphezu kwezinkulungwane zeminyaka. Ukwehla okuqhubekayo kweqhwa namazinga okushisa aphansi angaphansi kwezingu-0 degrees ngokuqhubekayo kubangela ukuba iqhwa linqwabelene endaweni efanayo, okulenza liguquke libe yiqhwa. Ama-glaciers yizinto ezinkulu kunazo zonke emhlabeni wethu futhi yize zibukeka zilungisiwe, ziyahamba. Zingageleza kancane njengemifula futhi zidlule phakathi kwezintaba zakha ama-crevasses kanye ne-glacial relief. Bangakha futhi amatshe namachibi.
Kulesi sihloko sizokutshela konke odinga ukukwazi ngamaqhwa eqhwa, imvelaphi yawo kanye nezici zawo.
Yini inguzunga yeqhwa
Inguzunga yeqhwa ibhekwa njengensalela yokugcina Ice Age. Ngalesi sikhathi, amazinga okushisa aphansi kakhulu aphoqa iqhwa ukuba liye ezindaweni eziphansi lapho isimo sezulu sesifudumele manje. Namuhla, singathola izinhlobo ezihlukahlukene zezinguzunga zeqhwa ezintabeni zawo wonke amazwekazi ngaphandle kwase-Australia nezinye iziqhingi ezisolwandle. Phakathi kwe-latitude engu-35° enyakatho no-35° eningizimu, izinguzunga zeqhwa zingabonakala kuphela ngaphakathi Izintaba ZaseRocky, e-Andes, eHimalaya, eNew Guinea, eMexico, eMpumalanga Afrika naseNtabeni iZard Kuh (Iran).
Inani lobuso izingulube zeqhwa elihlala kulo cishe kwakha u-10% wawo wonke umhlaba womhlaba. Imvamisa zivela ezindaweni eziphakeme zezintaba ngoba izimo zemvelo ziyavumelana nazo. Lokho wukuthi, kunamazinga okushisa aphansi nemvula ephezulu. Siyazi ukuthi kukhona uhlobo lwemvula olwaziwa ngegama lemvula yezintaba, olwenzeka lapho umoya uphakama phezulu bese ugcina upholile bese imvula iwela phezulu ezintabeni. Uma amazinga okushisa engaphansi kuka-0 degrees ngokuqhubekayo, lezi zimvula ziyoba ngesimo seqhwa futhi zizogcina zibeke kuze kube yilapho zakha izinguzunga zeqhwa.
Izinguzunga zeqhwa ezivela ezintabeni eziphakeme nasezifundeni ezipholile zithola amagama ahlukene. Lezo ezivela ezintabeni eziphakeme zibizwa ngokuthi amaqhwa e-alpine ngenkathi izinguzunga zeqhwa ezigxotsheni zaziwa ngokuthi ama-ice caps. Ngezikhathi zonyaka ezifudumele, amanye akhipha amanzi ancibilikayo ngenxa yokuncibilika kwawo, okwenza amanzi abalulekile ezilwaneni nasezimila. Ngaphezu kwalokho, awusizo olukhulu kubantu njengoba la manzi asetshenziswa abantu. Iyindawo enkulu yokugcina amanzi ahlanzekile emhlabeni, equkethe izingxenye ezintathu kwezine zawo. Ukuze uqonde inkimbinkimbi nesimo samanje sezinguzunga zeqhwa emhlabeni wonke, kubalulekile ukwazi ukuthi zinjani Izinguzunga zeqhwa zasePeru ziyashabalala ngezinga elishaqisayo futhi njengoba Izinguzunga zeqhwa zaseChina zisongelwa ukufudumala kwembulunga yonke.
Ukuziqeqesha
Ake sibheke ukuthi yiziphi izinyathelo eziyinhloko ezenzekayo zokwakhiwa kweqhwa. Siqukethe unomphela weqhwa endaweni efanayo unyaka wonke. Uma indawo inamazinga okushisa aphansi ngokungaguquguquki iqhwa ligcinwa kuze kwakheke iqhwa. Emkhathini, wonke ama-molecule omphunga wamanzi anamathela ezinhlayiyaneni ezincane zothuli bese enza izakhiwo zekristalu. Kungaleso sikhathi lapho amanye ama-molecule omphunga wamanzi enamathela kumakristalu akhiwa futhi amakhekheba eqhwa esijwayele ukuwabona akhiwa.
Amakhekheba eqhwa awela ezingxenyeni eziphakeme kakhulu zezintaba futhi agcinwa ngokuhamba kwesikhathi ngemva kokuwa kweqhwa okuqhubekayo. Lapho iqhwa elanele linqwabelana, izakhiwo zeqhwa ziqala ukwakheka. Unyaka nonyaka, isisindo sezingqimba ezintsha zeqhwa ezinqwabelanayo zenza ukuba iqhwa licwebezele futhi, njengoba umoya ophakathi kwamakristalu uncipha. Amakristalu aba makhulu futhi abe makhudlwana, futhi iqhwa elihlangene liyakhula ngokuminyana. Kwezinye izindawo ivumela ukucindezela kweqhwa bese iqala ukushelela phansi futhi bakha uhlobo lomfula okuthi ekugcineni ngakunye kube nokukhululeka okumise okwe-U.
Ukudlula kwenguzunga yeqhwa kungena emvelweni kudala ukukhululeka okwaziwa ngokuthi ukukhululeka kweqhwa. Kuyaziwa nangokuthi i-glacier modeling. Iqhwa liqala ukufinyelela kulayini wokulingana lapho ngenhla komugqa uthola isisindo esiningi kunalokho olahlekelwayo kodwa ngaphansi kwalo ulahlekelwa ngaphezu kwalokho okuzuzayo. Ngokuvamile le nqubo ithatha iminyaka engaphezu kweyi-100 ukwenzeka. Kufanele kuqashelwe ukuthi i- ukuguquka kwesimo sezulu kunomthelela izinguzunga zeqhwa eziningi e-Asia nakwezinye izingxenye zomhlaba, okubangela izinguquko emijikelezweni yazo yokwakheka. Ngakolunye uhlangothi, ucwaningo lubonisa lokho IMelika ingaphelelwa izinguzunga zeqhwa ngasekupheleni kwekhulu leminyaka uma izinyathelo ezifanele zingenziwa.
Izingxenye zeqhwa
Inguzunga yeqhwa yakhiwa izingxenye ezahlukahlukene.
- Indawo yokuqongelela. Yindawo ephakeme kakhulu lapho iqhwa liwela futhi liqoqeke khona.
- Indawo ye-Ablation. Kule ndawo izinqubo zokuhlangana nokuhwamuka zenzeka. Yilapho i-glacier ifinyelela khona ibhalansi phakathi kokukhuphuka nokulahleka kwesisindo.
- Ukuqhekeka. Yizindawo lapho i-glacier igeleza ngokushesha khona.
- AmaMoraines. Lawa ngamabhande amnyama akhiwa izidalwa ezakha emaphethelweni naseziqongweni. Amatshe ahudulwe yiqhwa ayagcinwa akhiwe kulezi zindawo.
- Isikhumulo. Kuphela ekugcineni kweqhwa lapho iqhwa eliqongelelekile liyancibilika khona.
Izinhlobo ze-glacier ezikhona
I-glacier ingahlukaniswa ngezindlela eziningi, nakuba kuncike ekubunjweni nasekubunjweni kwayo. Ake sibone ukuthi yiziphi izinhlobo ezahlukene:
- Iqhwa le-Alpine: Kuyaziwa nangokuthi igama leqhwa lentaba futhi yilawo akhiqizwa ezintabeni eziphakeme ngokuqongelelwa kweqhwa.
- Isekisi leqhwa: kuyisitsha esimise okweqanda lapho amanzi aqoqeka khona kancane kancane.
- Amachibi e-Glacial: Yizindawo zokubeka amanzi ezisukela ezindaweni eziphansi kwesigodi futhi kunezikhathi lapho ziba yiqhwa kanti ezinye zibe zingekho.
- Isigodi seGlacier: lo mphumela wesenzo sokuqhuma kolimi lweqhwa. Imvamisa inesigodi esimise okwe-U futhi yakha ukwakheka kwamadwala okude.
- I-Inlandsis: Ziyinqwaba yeqhwa elimboza yonke indawo futhi ligcine lidlulela olwandle.
- Ama-Drumlins: Yizindunduma ezakhiwe ngezinto ezisentabeni ezihudulwe yiqhwa lapho lihamba.
Sithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana neqhwa kanye nezici zalo. Uma ufuna ukujula ukuthi kanjani Izintaba zase-Himalaya zithintwa ukufudumala kwembulunga yonke, ungangabazi ukuphenya kabanzi.