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.
Nimbus clouds are cloud types that can indicate some type of precipitation. The word nimbus comes from the Latin language and stands for rain. There are two different types of nimbus clouds that indicate the type of precipitation. Continue Reading.