Translucidus
Translucidus (tr) ( Latin trans "beyond" and lucidus "shining") are clouds in extensive spots, fields or layers, which are mostly so transparent that the position of the sun or moon can be seen. This subspecies is mutually exclusive with opacus . The name is used for Altocumulus , Altostratus , Stratocumulus and Stratus .
Web links
Karlsruhe Cloud Atlas: