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.
Convective clouds may become very tall and are rounded on top. Clouds are also classified by their altitude and their ability to create precipitation. The root word âcirroâ (meaning âcurlâ) describes a high cloud that is usually composed of wispy ice crystals.The Latin word âaltoâ (âhighâ) indicates a cloud in the middle of the troposphere that is below the high cirro-type clouds. The prefix or suffix ânimbusâ (ârainâ) denotes a cloud that is causing precipitation.onvective clouds are as tall, or taller, than they are wide. These clouds look lumpy and piled up, like a cauliflower. Convective cloud types are indicated by the root word âcumulo,â which means âheapâ in Latin.