Hmm. An interesting idea. I've always thought though that we were sailing around the top of the clouds or higher, and thus rain was occurring below us. How are we doing this? Well, I've always imagined that the 'fifth' element envisioned by Aristotle (this in the days of the 4 elements being Fire, Water, Air, Earth) based on ideas concerning geometry by Plato, provided the necessary 'lift' for us and our ships. This fifth element, considered beyond the reach of mortals and relating to the realm of the gods, was called 'aether', and has provided plenty of imaginative ways of ordinarily impossible travel for science fiction writers from at least the Victorian age on (and if it was good enough for Jules Verne, it's good enough for me...). So, buoyed by the aether, our sky ships sail and wreckage takes a while to finally succumb to the pull of gravity. And the exposure to so much aether might also explain how our pirates manage to travel through the void between worlds and survive. Well, it provides a handy excuse for how things work in my mind, anyway!

But it seems likely powerful storms could mix up the lower atmosphere and the aether of the upper atmosphere, and bring dangerous weather to our ships. It's been known to happen... after all, some pirates' parents perished in a storm...

Virtuous Anne Radcliffe