IsAlahwe

IsAlahwe siyinhlwa yevanga enophawu u -Ar nenani lobuchwe eliyi-18. Siseqenjini le-18 lecansi lezinhlwa futhi siwuhowo oluntentemukayo. IsAlahwe siwuhowo lwesithathu oliyinala kakhulu kumoyambulunga woMhlaba, ngenani elingu-0.934% (9340 ppmv ). Siyinala ngokuphindwe kabili kunomhwamuko wamanzi (olinganiselwa ku-4000 ppmv, kodwa uhluka kakhulu), sigcwele izikhathi eziphindwe ngama-23 kunomcalahle ontuhlambili (400 ppmv), futhi siyinala izikhathi ezingaphezu kwama-500 kunenkanyihwe (18 ppmv). IsAlahwe siwuhowo oluntentemukayo oliyinala kakhulu egobohleni lomhlaba, sakha okungaba -0.00015% lwegobohla.