Kalmar "yankin D" na iya samun ma'anoni daban-daban dangane da mahallin. Anan akwai wasu ma'anoni kaɗan masu yuwuwa: A cikin ilimin kimiyyar ionospheric, yankin D yana nufin mafi ƙasƙanci na ionosphere, wanda ya tashi daga kimanin kilomita 60 zuwa 90 (mil 37 zuwa 56) sama da saman Duniya. Wannan yanki yana da girma da yawa na electrons kyauta, waɗanda ke sha tare da rage raƙuman rediyo a cikin kewayon mitar 1-10 MHz. Wannan ya sa ya zama da wahala ga sadarwa ta rediyo mai nisa ta faru a cikin wannan zangon mitar. A ilmin taurari, yankin D shine rarrabuwa na yankuna masu tabo da rana bisa la'akari da yanayin yanayin maganadisu. An rarraba yankunan Sunspot a matsayin A, B, C, D, E, F, ko H bisa lambobi da rikitarwa na wuraren hasken rana da filayen maganadisu, tare da yankunan D suna da tsaka-tsaki masu rikitarwa. A yanayin kasa, yankin D na iya komawa zuwa yankin kudancin Jamus, wanda ya kasu kashi biyar na tarayya da sunayen da suka fara da harafin "D": Baden-Württemberg, Bavaria, Berlin, Brandenburg, da Bremen. p>