Fear of falling - up!

Apropos nothing, here is a flying interlude...

I was flying my paraglider at the coast this weekend and cloud base was low, around 700 feet and I was at about 650 feet, moving reasonably slowly into the wind at just a few mph. For once cloud base at the coast was fluffy white cloudlets drifting overhead, not just an opaque blanket of fog (stratus) that you slowly disappear into while the ground (or ocean) melts away into white below you.

So I'm flying around at that height and starting to feel like the cloud is "coming right for me" because its blowing onshore at a reasonable speed and I'm so close to it. Then I notice when I'm looking up at the cloud just over my head and I start to feel a vertigo like dizziness coming on, like I was looking over the side of a tall building at the pavement, even to the point that I actually sensed some fear that I might fall up and hit the cloud... Granted that fear was perhaps well founded - cloud base can be a turbulent place to be where thermals peter out, and air layers mix up often violently - but I have a feeling it's source in this case was less rational and more primal, just like vertigo.

The solution was simple, just look down which when flying holds no ill feeling for me at all. But it was a weird experience and I'm now wondering if there is a name for the phenomenon.