The most regularly shaped waterfall is Skógafoss, like an elongated page of a book. Let us have the same kind of analysis as for the the other famous waterfalls at hand.
There was not much water in it during the winter time, but the edge of it can be clearly seen. From above the alignment can be measured and compared with calculated direction of convection rolls:
No surprise, because it fits exactly to the expected value.
And above Skógafoss there are at least 25 smaller falls within the Skógá river. Are they aligned according to a formula too?