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.
Nimbostratus clouds are smooth layers of gray, which often cannot be seen clearly because of the precipitation falling from them. Low clouds: Stratus, cumulus and stratocumulus clouds are based at altitudes of 6,000 feet or lower. Stratus clouds appear as smooth, even sheets; light rain and drizzle often fall from them; light snow or freezing drizzle during the winter. Fog is merely a stratus cloud reaching to, or forming on the ground.