On one night, late 19th century, a certain Fotheringhay stopped the
rotation of Earth. He omitted to cause air, water, loose items and
other corotating bodies to follow suit.
Eventually, he knew no better than return everything to its previous
condition.
If he had stopped the Earth and provided that everything corotating
should likewise stop, then the centrifugal forces should cease and the
equator would be some 21 km above poles. Air and oceans would promptly
(200...300 m/s, after a few hours of acceleration) slosh to the poles,
and the solid body of Earth would tend to flex in the same direction.
However, if he reversed the rotation of Earth (which would have solved
his immediate problem, that of preventing the moon from moving on),
the centrifugal forces would be unchanged.
The Coriolis forces, however...
If Coriolis forces instantly change sign, how long does it take for
trades and westerlies to overcome the inertia of moving air, and
reverse? What about the cyclones in being - does the changed
geostrophic force and the inertia of the rotation cause them to fill
and invert into anticyclones? What about ocean currents - how long
will the Gulf Stream need to reverse?
As for tides, reversing the rotation of Earth would change the tidal
period from 12 hours 25 minutes to 11 hours 35 minutes. A minor
change, but how far would the amphidromes move?
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