I-monsoon ivame ukuhlotshaniswa nezimvula ezinamandla, isiphepho, noma isiphepho. Lokhu akulona iqiniso ngokuphelele: i-monsoon ayisona nje isiphepho, kunalokho ukuhamba komoya endaweni ethile ngezikhathi ezithile zonyaka. Ngenxa yalokho, kungase kube nezimvula ezinkulu zasehlobo kanye nesomiso ngezinye izikhathi zonyaka.
I-monsoon (elisuselwa kwelesi-Arabhu elithi mawsim, elisho “inkathi”) ibangelwa umehluko wamazinga okushisa phakathi kwezwe nolwandle, kuchaza i-National Weather Service. Ilanga lifudumeza izwe namanzi ngendlela ehlukile, futhi umoya uqala “ukudonsa impi” futhi unqobe umoya obandayo, onomswakama ovela olwandle. Ekupheleni kwenkathi ye-monsoon, imimoya ibuyela emuva.
Izimvula ezimanzi ngokuvamile ziza ezinyangeni zasehlobo (ngoMbasa kuya kuSeptemba) ziletha izimvula ezinkulu. Ngokwesilinganiso, cishe u-75% wemvula yaminyaka yonke eNdiya futhi cishe u-50% esifundeni saseNyakatho Melika (ngokocwaningo lwe-NOAA) uwela phakathi nenkathi yezimvula zasehlobo. Njengoba kushiwo ngenhla, ama-monsoon amanzi aletha imimoya yolwandle emhlabeni.
Izimila ezomile zenzeka ngo-Okthoba-April. Izixuku zomoya owomile ziza eNdiya zivela eMongolia nasenyakatho-ntshonalanga yeChina. Zinamandla kakhulu kunozakwabo basehlobo. U-Edward Guinan, uprofesa wesayensi yezinkanyezi nesayensi yesimo sezulu, uthi iziphepho zasebusika ziqala lapho “izwe liphola ngokushesha kunamanzi nomfutho ophakeme ugcwala phezu kwezwe, uphoqelela ukuphuma komoya wolwandle.” Isomiso siyeza.
Minyaka yonke ama-monsoon aziphatha ngendlela ehlukile, eletha imvula encane noma enamandla, kanye nemimoya yesivinini esihlukahlukene. I-Indian Institute of Tropical Meteorology ihlanganise idatha ebonisa izimvula zaminyaka yonke zaseNdiya eminyakeni engu-145 edlule. Ukuqina kwama-monsoon, kuvela, kuyahlukahluka eminyakeni engama-30-40. Okubhekwe isikhathi eside kubonisa ukuthi kunezikhathi ezinemvula ebuthakathaka, enye yazo yaqala ngo-1970, futhi kukhona ezinzima. Amarekhodi amanje ka-2016 abonise ukuthi kusukela ngoJuni 1 kuya kuSepthemba 30, imvula ibe ngu-97,3% wenkambiso yesizini.
Izimvula ezinamandla kakhulu zibonwe e-Cherrapunji, esifundazweni saseMeghalaya eNdiya, phakathi kuka-1860 no-1861, lapho imvula engu-26 mm inetha esifundeni. Indawo enenani eliphakeme kakhulu eliphelele lonyaka (okubhekwayo eminyakeni engama-470) futhi isesifundeni saseMeghalaya, lapho kwehle khona isilinganiso esingu-10 mm semvula.
Izindawo lapho ama-monsoon avela khona yizindawo ezishisayo (kusuka ku-0 kuye ku-23,5 degrees enyakatho ne-latitude eningizimu) kanye nezindawo ezishisayo (phakathi kuka-23,5 no-35 degrees enyakatho neningizimu). Ama-monsoon aqine kakhulu abonwa, njengomthetho, eNdiya naseNingizimu Asia, e-Australia naseMalaysia. Ama-monsoon atholakala ezindaweni eziseningizimu yeNyakatho Melika, eMelika Ephakathi, ezindaweni ezisenyakatho yeNingizimu Melika, naseNtshonalanga Afrika.
Ama-monsoon adlala indima ebalulekile ezindaweni eziningi zomhlaba. Ezolimo emazweni afana neNdiya zincike kakhulu enkathini yezimvula. Ngokusho kwe-National Geographic, izitshalo eziphehla ugesi ngamanzi nazo zihlela ukusebenza kwazo ngokuya ngesizini yezimvula ezinkulu.
Lapho ama-monsoon omhlaba elinganiselwe imvula encane, izitshalo azitholi umswakama owanele futhi imali etholwa emapulazini iyehla. Ukukhiqizwa kukagesi kuyehla, okwanele kuphela izidingo zamabhizinisi amakhulu, ugesi ubiza kakhulu futhi ungafinyeleleki emindenini empofu. Ngenxa yokuntuleka kwemikhiqizo yokudla, ukuthengwa kwamanye amazwe kuyanda.
Phakathi nezimvula ezinkulu, izikhukhula zingenzeka, zibangele ukulimala hhayi kuphela ezitshalweni, kodwa nakubantu nezilwane. Izimvula ezinamandla zinomthelela ekubhebhethekeni kwezifo: ikholera, umalaleveva, kanye nezifo zesisu nezamehlo. Eziningi zalezi zifo zisakazwa ngamanzi, kanti nezindawo zamanzi ezithwele kanzima azikho ezingeni lokwelapha amanzi okuphuza nezidingo zasendlini.
Isistimu ye-monsoon yaseNyakatho Melika nayo ibangela ukuqala kwenkathi yomlilo eningizimu-ntshonalanga ye-United States nasenyakatho yeMexico, kusho umbiko we-NOAA, ngenxa yokwanda kombani okubangelwa izinguquko zokucindezela kanye nezinga lokushisa. Kwezinye izifunda, amashumi ezinkulungwane zokushaywa kombani abonwa ngobusuku obubodwa, okubangela imililo, ukuphelelwa amandla kanye nokulimala kanzima kubantu.
Iqembu lososayensi baseMalaysia lixwayisa ngokuthi ngenxa yokufudumala kwembulunga yonke, ukwanda kwemvula ngesikhathi sezimvula zasehlobo kufanele kulindeleke eminyakeni engu-50-100 ezayo. Amagesi abamba ukushisa, njengesikhutha, asiza ukubamba umswakama owengeziwe emoyeni, onisa ezindaweni esezigcwele izikhukhula. Phakathi nenkathi eyomile yeziphepho, umhlaba uyokoma kakhulu ngenxa yokwanda kwezinga lokushisa lomoya.
Esikhathini esincane, imvula ngesikhathi sezimvula zasehlobo ingashintsha ngenxa yokungcoliswa komoya. I-El Niño (ukushintshashintsha kwezinga lokushisa ebusweni boLwandlekazi iPacific) iphinde ithinte iziphepho zaseNdiya esikhathini esifushane nangesikhathi eside, kusho abacwaningi baseYunivesithi yaseColorado eBoulder.
Izici eziningi zingathonya ama-monsoon. Ososayensi benza konke okusemandleni abo ukubikezela izimvula nemimoya yesikhathi esizayo - lapho sazi okwengeziwe ngokuziphatha kwezimvula ezinkulu, umsebenzi wokulungiselela uzoqala ngokushesha.
Uma cishe uhhafu wabantu baseNdiya beqashwe kwezolimo kanye ne-agronomy ifinyelela cishe u-18% we-GDP yase-India, isikhathi semvula enkulu nemvula singaba nzima kakhulu. Kodwa, ucwaningo olwenziwa ososayensi lungahumusha le nkinga ibe yisixazululo sayo.