Affa (s Tegnizt: Radiance) d tasmekta n tfasa n tafat i d-iteffɣen deg yiwet n tsint seg 1 cm2 seg kra n tjumma iteddun ɣer kra n tnila s talɣa taratakt i teɣmert tuntimt. Tigget n waffa deg unagraw agreɣlan n tiggtin iga d watt i yal amiter amkuẓ i yal ustirdyan (W·sr−1·m−2), anda tajumma (m³) tettili d taratakt deg tnila n tafat Asegder n tafat deg yilem yeṭṭafar tadɣert d tnila. Amedya, Tasfawt (llamba) i d-iberrun i tadla n tafat deg texxamt tamsullest mi ara ad yettwassen wadeg n tesfawt d tnila deg wacu i d-ittak tafat yettak-d tazmert i weglam n tesfawt. Anecta yennumk d akken kra n tajumma meẓẓiyen iwulan ɣer uɣbalu n tafat seg zdat tetteɣlay-d fellas tfasa meqqren s wassaɣ ɣer tjumma ur nwula ara srid i tafat Seg tsekna tixatarin yakk n waffa d akken iga d imezgi n watig deg uzerrig aɣɣad, dɣa taskent-a tettusemres s tuget deg yisnasen tsekdanin. S yis yezmer ad tili tussna n tassast n usefliley n tfukt d yitran. Asumer n tafat d akken-it ur tettwasemdu ara s wammas deg wanda i d-tettenfufud deg-s yettili d imezgi gar n sin n wazagen P1 d P2, atig n waffa yettaǧǧan azag P1 deg tnila n P2 yegda atig n waffa i d-ittawaṭen ɣef wazag P2 seg tnila P1. Asiden Ẓeṛ daɣen == Imniren ==