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.
Strato-cumulus clouds are low, puffy, and gray. Most form in rows with blue sky visible in between them. Rain rarely occurs with strato-cumulus clouds; however, they can turn into nimbo-stratus clouds. A sky full of strato-cumulus clouds indicates dry weather, a small difference in temperature from day to night, and sometimes light precipitation.