Why is this confusing? We aren't comparing planets by amount of water they have. I thought the goal of this visualization was just to make a point - the amount of fresh water in rivers and lakes appears to be the size of a large metropolis in radius. Seems like a cool way to show scale of water resources
Well, let me put it this way: that apparently little fresh water sphere? If the ISS passed over that spot, it would hit that.
This is the point: everything on the surface of the Earth is essentially two dimensional at this scale. Seeing a sphere with a 400 km radius placed on the Earth doesn’t give any better intuitions for the scale of water resources than simply reading the number “35 quintillion liters”. If you think it’s given you a better intuition, you’ve been misled.
