It is commonly called alumina, and may also be called aloxide, aloxite, or alundum depending on particular forms or applications. It commonly occurs in its crystalline polymorphic phase Î±-Al 2 O 3, in which it composes the mineral corundum, varieties of which form the precious gemstones ruby and sapphire.
rain cloud. (meteorology). Any cloud from which rain falls; a popular term having no technical denotation. 1  Facebook. 2  Twitter.
, I'm no cloud expert, but I know some things about clouds. What is called a nimbus cloud is a cloud that produces precipitation. In the warmer months (or in places where it's warm year round), precipitation that falls from these clouds is primarily rain. But, in the colder months (or in places where it's cold year round), precipitation is primarily snow, though other forms of icy precipitation may fall from nimbus clouds.