[SPACE] Tidal braking

[Agemegos]

Originally Posted by Figleaf23

I'm curious -- do the tide height calculations assume there is surface water? Does there have to be surface liquids? What about other substances like a sea of amonia -- would it matter?

What is calculated is the equilibrium tide height, which is the tidal height that the surface will tend to given indefinite time. A liquid surface will approach the equilibrium fairly quickly, mantle material will do so only over tens of thousands of years. If you have a mixed surface of solids and liquids the oceans will tend to conform much more rapidly than the land, and you will get the phenomena that we know as tides: the oceans rising and falling with respect to the land. That will involve sloshing and (in some bodies of water) resonance effects. These can result in local tides in some bays and straits much larger than the equilibrium tidal range. For example, the equilibrium tide on Earth has an amplitude of about 0.6 m, whereas some bodies of water such as the Bay of Fundy and King Sound have tidal amplitudes ten of fifteen times that.