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.
For example, middle cumulus clouds are called altocumulus and high stratus clouds are cirrostratus.. If a cloud produces rain or snow it gets either nimbo at the beginning or nimbus at the end. Cumulus clouds are low individual billowy globs that are low, have flat bases and look a little like cauliflower.