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.
Cirrus clouds are very high in the atmosphere where the air is very cold. These clouds of ice crystals are usually associated with fair weather, but may sometimes indicate that storms are on their way. Cirrostratus Clouds -. Cirrostratus clouds are milky, white-veined clouds that produce a halo around the sun or moon.