Description & Characteristics. The ‘radiatus’ cloud variety can be found amongst five cloud types: cirrus, altocumulus, altostratus, cumulus, and stratocumulus. Translated from latin, meaning striped, the five types of radiatus clouds are respectively abbreviated as ‘Ci ra’, ‘Ac ra’, ‘As ra’, ‘Cu ra’, and ‘Sc ra’. Radiatus cloud formations are best identified as clouds that are arranged in parallel rows that when observed from the right perspective, they appear to converge at a single point on the horizon. They can also be referred to as cloud streets.
The cloud varieties radiatus and undulatus are somewhat similar in nature and presentation; they can both be arranged in lines. In order to tell the difference between the two, it’s important to note that undulatus clouds are transverse to the direction (perpendicular) of the wind, whereas radiatus clouds form in the same direction (parallel) of the wind. This explains why radiatus clouds will appear to radiate out from the horizon.
When the radiatus cloud variety is observed in cirrus clouds, it’s more common to find them as the fibratus cloud species in relation to other cloud species. Altocumulus radiatus clouds can be found in the castellanus, floccus, or stratiformis cloud species and aren’t typically associated with the lenticularis and volutus species. Observed in altostratus clouds, the radiatus variety appears as streaks in the otherwise featureless cloud layer. When the radiatus cloud variety is observed as cumulus and stratocumulus clouds, the formation is often referred to as a cloud street as the clouds are found lined up in rows.