ruwan sama ruwa ne da ke sauka daga sama wanda Allah (S.W.T) shi ne ya ke saukar da shi a kowane lokaci dare ko rana, wani lokaci ya yi yawa wani lokaci kuma ya yi kadan, amma mafi yawa ya fi zuwa da hadari, wanda hausawa suke mashi lakabi da (ruwa kaman da bakin kwarya). Sai kuma yayyafi, shi yayyafi mafi akasari yana zuwa ne a hadarin da bai saukar da ruwa ba, sai kuma misali lokacin marka-marka shi kuma a wannan lokacin zaka ga ruwa ba dare ba rana. A wani lokaci ruwan yayi karfi wani lokacin kuma baya yin karfi, to wanda bai yi karfin ba shi ne ake kira da yayyafi. . A Larabci ana kiransa da "مطر". Shi dai hadari shi ne kusan ace ginshikin ruwan sama wanda mafi yawan ruwan saman da ake yi sai hadari ya hadu ya taso yayi iska sannan sai ruwa ya zo, wani lokaci a hade da iska wani lokacin kuma zallan ruwan ne. Menene Hadari ?