Altocumulus Radiatus

Credit s0ulsurfing – CC-BY-NC-ND

Cloud of the Day – Altocumulus Radiatus

Altocumulus radiatus is defined as clouds arranged in parallel lines that appear to converge at a central point near the horizon. Conversely, they could be said to appear to radiate from a central point, hence the radiatus in the name. Of course they aren’t really converging or radiating. They only appear to be because of perspective. In open country or on the sea, the horizon is a lot farther away than the clouds overhead. Our minds are tricked by their tendency to assume that they are roughly equally distant. That our sky is bowl shaped and the overhead dome is as far away as the horizon. So, even though the lines of altocumulus clouds are parallel and so just as far apart at the horizon as they are directly overhead, we see them as converging and radiating.

Credit followtheseinstructions – CC-BY-SA

Altocumulus radiatus are not indicative of any particular weather. They’re just something that stands out and can be given a name, and we humans do like to do that, don’t we?

Credit Nicholas A Tonelli CC-BY

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