ventus1b t1_jdli5br wrote on March 25, 2023 at 7:37 AM

Reply to comment by HeebieMcJeeberson in If earth was a smooth sphere, which direction would water flow when placed on the surface? by Axial-Precession

Also if it was a perfectly smooth sphere where there is no friction to accelerate the water?

Wouldn’t the water then just sit as a sphere around the spinning earth?

mfb- t1_jdln32i wrote on March 25, 2023 at 8:51 AM

If it's placed at rest relative to the ground then it would flow towards the equator.

If it's placed at rest relative to the center of Earth and we could magically avoid any friction (no surface can do that completely with water) then it would just spread out.

ventus1b t1_jdlozis wrote on March 25, 2023 at 9:20 AM

Yes, thanks for reminding me of that distinction.

I was thinking of water at rest wrt to Earth. Or both at rest and Earth spinning up.

HeebieMcJeeberson t1_jdx0byy wrote on March 27, 2023 at 8:25 PM

For one thing, perfect smoothness doesn't eliminate friction - there's also electrostatic attraction between molecules. Eventually the planet rotating under the water would coax it to move.

But moreover, the atmosphere would be screaming by overhead since it does rotate with the Earth. The atmosphere is chaotic, with zones of different pressures which press down on bodies of water unevenly, creating irregularities that the sideways wind can act on to create waves. This is how wind stirs up waves on calm, smooth lakes and such.