Liquid hydrogen on Jupiter

[Ashok Narayan]

I wonder why it is often said that on Jupiter, in between gaseous Hydrogen and metallic Hydrogen, there is a layer of liquid Hydrogen. I believe that below the Jovian atmosphere Hydrogen can exist only as "critical fluid" (above the critical temperature); liquid phase of Hydrogen cannot exist.

[Hornblower]

I wonder why it is often said that on Jupiter, in between gaseous Hydrogen and metallic Hydrogen, there is a layer of liquid Hydrogen. I believe that below the Jovian atmosphere Hydrogen can exist only as "critical fluid" (above the critical temperature); liquid phase of Hydrogen cannot exist.

I think you are correct there. The temperature at the cloud tops is way above the critical temperature of hydrogen, and it will get warmer below that level. It should remain a gas until the phase change to metallic.

[grant hutchison]

I wonder why it is often said that on Jupiter, in between gaseous Hydrogen and metallic Hydrogen, there is a layer of liquid Hydrogen. I believe that below the Jovian atmosphere Hydrogen can exist only as "critical fluid" (above the critical temperature); liquid phase of Hydrogen cannot exist.

I think it's an approximation, chosen for those who don't know the difference between a liquid and a fluid. Although the hydrogen is above its critical point (making it a "supercritical fluid"), in the deep layers of the Jovian atmosphere that fluid will behave very much like a hot, dense liquid. The only difference is that there is no point in the atmosphere at which we can identify a phase transition from gaseous to liquid.

Grant Hutchison