Matsayi na farko galibi ana gane shi a cikin yanki, wanda aka bayyana ta tasirin tasirin ƙasa, wanda aka sani da Layer iyaka ta duniya. Cikakken iska mai rikicewa ne ya mamaye shi, wanda aka samar dashi ta hanyar dorewa dindindin tare da yanayin ƙasa mai ƙarancin ra'ayi da kuma haɓakar iskar kumfa a yayin da yake zafi.
Wannan Layer ne bisa ga al'ada sanya a tsawo daga 600 zuwa 800 m, amma zai iya zama daga fewan mitoci goma zuwa kilomita ɗaya ko biyu, ya danganta da dalilai kamar yadda yanayinsu ya bambanta, yanayin yanayin ƙasa, yanayin murfin ciyayi, tsananin iska, yanayin dumama ko sanyaya ƙasa, zafi mai zafi da zafi, da sauransu. Da rana, shigarwar zafi da hadawar iska a tsaye yana kara kaurin layin iyaka, wanda ya kai matsakaicin tsayi da sanyin safiya; akasin haka, cikin dare sanyayawar ƙasa yana hana hayaniya kuma an rage kaurinsa.
Wasu lokuta, ƙari, tsarin tsaye na layin iyaka yana ba da damar bambance matakan da yawa:
1) a Laminar layin kwayoyin, a cikin ma'amala da ƙasa, kaɗan thickan milimita kauri, mamaye sakamakon tasirin ɗanko na farfajiya;
2) sannan a m Layer da yawa tsayin mitoci, halin tsananin tashin hankali na iska; kuma
3) matakin sama, inda Coriolis ke aiki akan iska, ana kiran sa ekman kabido.
Tuni a saman sararin samaniya mai kyauta yake, tare da tsaftacewa da iska mara ƙarancin ƙarfi, inda zafin jiki ya sauka a matsakaicin ƙimar 6 ºC / km.