Kokubili ezincwadini zokufunda nasezithombeni zesikhathi somuntu, iplanethi yethu ibonakala inomumo oyisiyingi. Nokho, lokhu akunjalo ngokuphelele. I ukuma kwangempela komhlaba yehlukile. Abantu abaningi bayazibuza ukuthi uyini umumo wangempela woMhlaba.
Ngalesi sizathu, sizonikezela lesi sihloko ukuze sikutshele ukuthi uyini ukuma kwangempela komhlaba, izici zawo nokuthi kungani udwetshwa ngaleyo ndlela.
ukuma kwangempela komhlaba
Nakuba kungase kubonakale kumangalisa, uMhlaba awuyindilinga ngokuphelele, kodwa kunalokho uphansi ezigxotsheni futhi uqhuma enkabazwe. Lo mumo waziwa ngokuthi i-geoid futhi kungenxa yokuhlanganiswa kwezinto ezimbalwa., njengokujikeleza koMhlaba ku-eksisi yawo, amandla adonsela phansi kanye nokusatshalaliswa kobunzima boMhlaba. Ngamanye amazwi, ukuma koMhlaba kuthintwa amandla awo adonsela phansi kanye nokusabalalisa kobunzima bawo.
Ukuze ukuqonde kangcono lokhu, ake ucabange ukuthi uMhlaba uyibhola le-plasticine elijikeleza eksisi yalo. Ngenxa yamandla okujikeleza, ubumba luya ngaphandle enkabazwe, kuyilapho ezigxotsheni luhamba kancane.
Nokho, Nakuba umhlaba ungewona oyindilinga ngokuphelele, ukuma kwayo kufana nendilinga engaphelele. Ngenxa yalesi sizathu, iminyaka eminingi kwakukholelwa ukuthi uMhlaba uyindilinga ephelele. Kwaze kwaba emakhulwini ambalwa eminyaka adlule lapho ososayensi baqala khona ukufunda kabanzi ngesimo soMhlaba futhi bathola ukuthi wawuyisicaba ezigxotsheni futhi uqhuma enkabazwe.
Okusha okutholakele
Inqwaba eyakha uMhlaba ayifani. Umehluko umakwa ngamashidi eqhwa ashubile noma azacile, ukugeleza kwamanzi angaphansi komhlaba, ukuhamba kancane kwe-magma ekujuleni, nokunye okuguquguqukayo kwezwe okuningi. Njengoba ubukhulu bawo bungafanani, umkhakha wamandla adonsela phansi nawo awufani. Umehluko mncane kakhulu, ungaphansi kuka-1% phakathi kwamaphuzu adlulele kakhulu.. Izilinganiso ezibanzi zithathwe umkhankaso we-NASA oqanjwe ngowesifazane, u-GRACE (Isi-Spanish for Gravity Recovery and Climate Experiment). Umsebenzi wokuqala ka-Grace kwakuyimephu eyihaba yenkambu yamandla adonsela phansi elingana nehomogeneous: i-sphere enombala ecwile eNdiya.
Ukuma kwangempela komhlaba kufana nezambane. I-European Space Agency (ESA) isibonise ngobuhlakani ukuthi imephu yomhlaba edonsela phansi ingabukeka kanjani ekufanisweni kwevidiyo. Ukuze benze lokhu, bathembele kudatha eqoqwe ku-Gravity Field kanye ne-Steady State Ocean Circulation Explorer (GOCE). Lona uphenyo lwe-ESA olude lwamamitha amahlanu ubude be-Arrowhead, obulokhu luzungeza emzileni ophansi we-Earth cishe iminyaka emibili. Umsebenzi wayo oyinhloko ukuqoqa idatha emkhakheni wamandla adonsela phansi weplanethi ukuze uhlaziye ukuthi usebenza kanjani emhlabeni wonke.
Njengoba kuchazwe ithimba labacwaningi elibhekele i-GOCE, umhlaba empeleni uyi-geoid. Ungase uthi iplanethi yethu inendawo okungathi uma ubeka imabula noma yikuphi, ihlale lapho esikhundleni sokugingqika. Enye incazelo, mhlawumbe enembe kakhudlwana, nakuba ichwepheshile kakhulu, ukuthi umumo we-geoid yizo zonke izifunda zayo lapho inkambu yamandla adonsela phansi ime mpo. Uma singahamba ngezinga elikhulu ku-geoid, besizobona ukuthi amandla adonsela phansi ahlala ekhomba phansi ngqo. Nakuba isisindo sawo asifani ngaso sonke isikhathi. Amandla adonsela phansi awafani yonke indawo.
Ngokuvamile, kunokungaqondi kahle mayelana nemiqondo emibili yokubala ye-multivariate evame ukudideka: izinkambu ze-vector namandla azo. Kulesi simo, inkambu ye-vector iyinkambu yamandla adonsela phansi futhi amandla angaba namandla adonsela phansi. Lokhu kwakamuva kungahunyushwa njengamandla adonsela phansi ngamayunithi obunzima. Ngakho, nakuba inkambu yamandla adonsela phansi ingahlukani kunoma yisiphi isifunda se-geoid, okungukuthi, ihlezi idonsela ohlangothini olufanayo, amandla adonsela phansi angahluka. Ngale ndlela, isisindo sakho singahluka kancane kusuka endaweni eyodwa kuya kwenye.
Amandla adonsela phansi awafani emhlabeni wonke
Umhlaba uyi-geoid ngezizathu eziningana. Esinye sazo yilesi esisitshela ukuthi izigxobo zenziwa isicaba nge-centrifugal force. Kodwa njengoba sesibonile, Umhlaba awuyona i-ellipsoid ephelele futhi, njengoba ukubunjwa komhlaba okuhlukile kuguquguquka endaweni yawo.
Izintaba nezigodi ziyi-asymmetrical rock formations enama-thrust amabili aqondile. Okokuqala ukuthi ukusatshalaliswa okungalingani kwesisindo kuthinta amandla adonsela phansi. Okwesibili, ngakho-ke, ukuthi uphendulela uMhlaba ube yindilinga esakazwa ngokulinganayo, okungukuthi, uphendulela uMhlaba ube yi-geoid.
Okunye okunganakwa uma kubhekwa ukuma koMhlaba ukuthi ingxenye enkulu yomhlaba imbozwe ngamanzi. Nakuba singakuqondi ngokugcwele ukujula kolwandle, kodwa siyazi ukuthi nalo lwenziwe ngezimo zomhlaba. Futhi, izilwandle azilingani, futhi nakuba "izinga lolwandle" laziwa njengesilinganiso esinembile kuzo zonke izifunda, amazinga amanzi awafani emhlabeni wonke, ngoba usawoti kasawoti awufani kuzo zonke izilwandle.
I-geoid yomhlaba ayisona isimo sangempela seplanethi yethu, noma ukuthi ibingabukeka kanjani uma sisusa izilwandle. Ifanekisela indawo elingana ne-equipotential Yomhlaba, noma indawo efanayo lapho amandla adonsela phansi ame mpo kuwo wonke amaphuzu (yingakho imabula ingagingqiki ngoba izwa kuphela ukusheshisa okuya phansi), ngaphandle kwezinye izici.
Okubaluleke kakhulu, ezithombeni ezivela ezifundweni zomumo wangempela woMhlaba, izigodi namagquma kweqiwa (ubude noma ukujula) ngenani elingu-7000 uma kuqhathaniswa neqiniso. Ngokungafani nomhlabathi, lapho umehluko phakathi kwephuzu eliphakeme kakhulu (i-Everest 8.848 metres) kanye nephuzu eliphansi kunazo zonke (uLwandle Olufile -429 amamitha) lukhulu, i-geoid iyahlukahluka kusuka ku--106 kuya ku-85 amamitha, ngamamitha angu-200 kuphela okungalingani.
Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana nesimo sangempela soMhlaba kanye nezici zawo.