Official Classification?

As a fanatical cloud spotter, I tend to spot the difference between cumulus mediocris radiatus and altostratus translucidus. K is convinced that I make the names up as we drive along and I slip the odd classification into our regular conversation. But I don't make it up; far from it. The study of clouds is a rather specific science within the subject of meteorology. In fact, there are more than 30 varieties within 12 different species of 10 distinct genus of cloud (did you follow that?). 

So I just had to take a photo of this beautiful specimen last week. Problem is, I've been studying my various books on cloud genus (yes, I admit to possessing a rather large, sad collection) and I can't identify this one. The time has come for me to contact the ultimate cloud guru for advice; Gavin Pretor-Pinney, the Chairman of the The Cloud Appreciation Society. Answer hopefully to follow....