Amazinga emvula achazwa njengemvula encinci, ephakathi okanye enkulu kuxhomekeka okokuba imvula ingakanani eyehlileyo ngeyure. Umzekelo imvula encinci – 2.5 mm, ephakathi – 2.8 ukuya ku 7.6 m ze imvula enkulu ebengapha ko 7.6 mm ngeyure.
Ngokwe South African Weather Service, I-1 mm yemvula ilingana ne litha enye (1) yamanzi kwi 1 m 1 m indawo apho amanzi angachitheki ecaleni, angahluzwanga okanye umphunga.
Ukwenzeka Kwemvula
Imvula yenzeka emafini. Amafu enzeka xa kusonyuka umoya ofumileyo. Umoya lowo uthi wande, ngenxa koxinzeleko oluse zantsi oluphezulu emoyeni, ze uphinde uphole. Umoya opholileyo uye usasazeke ngomphunga wamanzi kulapho ke kuthi umphunga ujike ubengamanzi. I ‘condensation’ kuxa amaqabaza amanzi esenzeka kwindawo ebandayo okanye ajikeleze indawo. Xa ukwenzeka kwamaqabaza emvula kuqhubekeka, lamaqabaza amanzi ayakhula de asinde ukonyukela phezulu komoya ze awe emhlabeni.Amafu
Amafu Stratiform clouds afana nengubo kwaye ogquma indawo enkulu. Lamafu enzeka xa ukuphinda phindana komoya kunyanzeleke okokuba konyuke kancinci-kancinci kum-mandla wendawo enkulu, wenze ukuphinda phindana. Xa umphezulu ufumile kwaye ukonyuka kuyaqhubeka, istratiform clouds zingazisa imvula enkulu okanye ikhephu.
Amafu aziwa ngokuba yi Cumuliform clouds, wona angqukuva okanye afana nesikhanyisi ngembonakalo, aye enzeke ukujonga phezulu. Lentshukumo yokujonga phezulu yenza amafu we cumulonimbus angqindilili, amade athi azise iindudumo.
Ucalulo lwe Mvula
Imvula i-Convection
Yenzeka xa umoya ofumileyo unyuka usuku emhlabeni. Cumulonimbus okanye cumulus clouds zenzeke ze imvula ize ngendudumo.
Iindudumo zidityaniswa nomoya onamandla, ovuthuzayo, imvula enamandla maxa wambi ehamba nesichotho. Kwindawo ezisentlango, amachaphaza amanzi asuka kwindudumo anganyuka nje ngomophu phambi kokuba afikelele emhlabeni.
Iimvula ezinjalo ziyenzeka ehlotyeni kwindawo ezisentlango ezitshisayo apho kukho ingqokelela yokufuma emoyeni nobushushu.
Imvula i- Orographic
Yenzeka xa umoya ofumileyo unyanzeleke unyukele phezulu kwicala lentaba. Nimbostratus clouds ziyenzeka ze imvula yehle kwicala eliza umoya (umoya oyaphezulu) kwentaba. Imvula iza ezantsi kwicala (lomoya owehlayo) kwintaba. Lendawo ichazwa ngokuba ‘sisithunzi semvula’.
I-Little Karoo, engqunge i-Oudtshoorn, ngowona mzekelo oncakasana wesithunzi semvula kweli lo Mzantsi Afrika. imvula kwicala eliza umoya. Ngase lwandle, kwicala lentaba zase Outeniqu ungaba ngapha kwama 1 000 ngonyaka, kakhulu kwicala le Little Karoo, umoya owehlayo entabeni, ungaphantsi ko 200 mm.
Imvula i-Frontal okanye i-Cyclonic
Yenziwa ngumoya osezantsi ongqongileyo, umoya namafu. Oku kwenzeka xa umoya oshushu, oshushu ozangaphambil, udibana nengqele evela ngase lwandle ze kwenzeke ilifu, indawo esezatsi esiphakathini ze ibephezulu kwengqongileyo.
Umoya oshushu unyanzeleka wonyuke ngaphezulu komoya obandayo. Umoya onyuka esiphakathini uyaphola, wenze inimbostratus clouds ze yenze imvula enamandla kulondawo.
Translated by Zikhona Plaatjie