  D2 implies that being a cloud is an  intrinsic  property. The idea is that by changing the world outside the cloud, we do not change whether or not it is a cloud. There is, however, little reason to believe this is true. And given that it leads to a rather implausible conclusion, that there are millions of clouds where we think there is one, some reason to believe it is false. We can argue directly for the same conclusion. Assume many more water droplets coalesce around our original cloud. There is still one cloud in the sky, but it determinately includes more water droplets than the original cloud. The fusion of those water droplets exist, and we may assume that they did not change their intrinsic properties, but they are now a part of a cloud, rather than a cloud. Even if something looks like a cloud, smells like a cloud and rains like a cloud, it need not be a cloud, it may only be a part of a cloud.