The Cloud Base is one of the bases used by Thunder Cloud. It's located inside of a cloud, and has an incredibly sophistocated telescope that allows the heroes to look out on the world.
Return of the Thunder CloudEdit
The Cloud Base was first discovered by Thunder Boy when he was fighting Diamond Men in the sky. For many years, the team used it as a base. When they reached adulthood, having long since abandoned their superhero identities, the base had been long abandoned and it was uncertain whether it even still existed. ("Return of the Thunder Cloud")
The NuLabs ConspiracyEdit
The Cloudbase features prominently in this game. ("Thunder Cloud: The NuLabs Conspiracy")