A cloud is more than just coalesced water vapor. If it were then fog, mist and steam would all be considered a cloud. In truth, some definitions do say exactly that. However, we communicate most effectively when words have clear and distinct meanings. If I were to ask you to visualize a cloud, you would think of the puffs of grandeur in the sky. No matter what you think of in addition, that image would be invoked. Even if you are unsure of the context, that image would be amongst the most likely possibilities. Sky clouds, as envisioned, do require water vapor but they also require air, space, pressure and light to form that common image.
What's the point? The point is that the word, 'cloud', has a commonly understood meaning, regardless of the technical or scientific details that can make that specific meaning less exclusive. No one is served by making the definition more ambiguous. Similarly, the description and components of cloud computing should not be watered down to allow every conceivable enterprise feature or outcome.
Cloud computing is a way to maximize capacity and utilization and to minimize space, maintenance and to simplify governance. It offers these benefits by employing virtualization concepts and capitalizing on the emergence of patterns in enterprise topologies.
Virtualization is not a cloud solution, but a cloud solution will require virtualization in some form, whether it be cloning or full virtual images. Similarly, parallel processing on pooled resources is not a cloud but the principles of that are important to the conception of an effective cloud. However, a cloud also requires understanding of the enterprise, a clear picture of patterns and topologies and an efficient process for managing images as distinct entities. In other words, it's not just water vapor.
Cloud computing is the product of the evolution of networks and enterprises. It requires many things that have existed for years but only now have developed to the point where we can achieve the power and flexibility that cloud computing offers. Weighing down the grandeur of the cloud concept by overemphasizing some constituent part or by understating the importance of its management and governance serves no one except for the few trying to get a free ride in the sky.