Several things. People have long wondered, why has the Great Red Spot been around for such a long time? The Great Red Spot is a storm, and we are used to storms on Earth. The average hurricane lasts a couple of weeks at most, and it has a definite mechanism for destruction: It either goes into cool water, which cuts off its fuel supply, or it goes over land, which really cuts off its fuel supply. Tornadoes are quite impressive, but they’re very ephemeral—they only last a few hours. So why do we have a Great Red Spot lasting so long? People used to say, “Oh, it’s clouds hanging around a mountain top.” Or “It’s an iceberg in a sea of hydrogen.” Those theories pretty much stopped around 1979, when Voyagers 1 and 2 flew by the planet. Nobody really knew it was a vortex, a huge hurricane that takes about six days for a single rotation. The United States would fit into the Red Spot a couple of hundred times. I mean, it’s really huge. One of the great things about the Voyager missions was that they took hundreds of pictures of the clouds that make up the Red Spot, so we could finally see the whole thing swirling around, and that’s how we knew for sure it was a vortex. Nobody knew it was really spinning. [...]
The harvest of that energy is what balances the loss of the Great Red Spot’s energy from thermal radiation. In a computer simulation, you can actually measure the direction and magnitude of all the energies that go in and out of the Great Red Spot, and the whole energy budget balances very nicely. You’ve got this great drain of potential energy in the atmosphere in the area surrounding the Great Red Spot due to this circulation of gas, but it’s OK because the sun re-establishes radiative equilibrium in that surrounding area and re-supplies its energy. So, ultimately, the source of energy that prevents the Great Red Spot from being destroyed is the sun. [...]
I am speculating that the Red Spot is, from top to bottom, somewhere between 50 and 70 kilometers tall. From side to side, it’s about 26,000 kilometers. So it’s a pancake. Just like with a tube of toothpaste, if I squish the pancake with high pressure at its center, something is going to squirt out the sides and top and bottom. It’s known that the Great Red Spot has a high pressure at its center, but its gases don’t go squirting out horizontally from its sides because of the Coriolis force in those directions—instead they squirt out vertically from the top and bottom. So, what can prevent the gases from squirting out vertically? The only way that I know to prevent that is if the top of the Great Red Spot has a dense cold lid of atmosphere above it. It’s that extra density that pushes the gases in the Great Red Spot back down. And, below the Great Red Spot, there must be a warm buoyant floor of atmosphere, and that floor prevents the high pressure center from pushing the gases in the Great Red Spot downward and out its bottom. That’s the balance.
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