Tsunami clouds.

[dennilfloss]

I'd definitely feel uneasy too if I saw this weather phenomenon rolling towards me...

http://travel.aol.co.uk/2012/02/08/amazing-pics-tsunami-waves-clouds-hit-floridas-coast/

 

[Rubycon]

We've seen this before at sea. It's far less dramatic as there's no obstacles for it to play with. Most of the time they're small puffs that seem to "billow" from the sea. Other times they are much thicker, more organized and if lucky one can see half the ship and not the other on the approach. Lots of myths about "The Fog".

 

[dennilfloss]

The Fog reminds me of Adrienne Barbeau and her obstacles.^_^

 

[ThatsABigOne]

That is the magic of poor aerodynamics.