Equipotential

Lines of constant ψ are known as streamlines and lines of constant φ are known as equipotential lines (see equipotential surface ).

When the equipotential lines for φ(z) lie close, the number is large, and conversely, therefore the equipotential lines for the function should lie approximately regularly.

Height is a measurement at right angles to this surface, roughly toward the centre of the Earth, but local variations make the equipotential layers irregular (though roughly ellipsoidal).

If we colour the Fatou domain according to the iteration number (and not the real iteration number), the bands of iteration show the course of the equipotential lines.

The equipotential lines for this function are concentric circles.

The ocean surface moves because of the changing tidal equipotential, rising when the tidal potential is high, which occurs on the parts of the Earth nearest to and furthest from the Moon.

This is the primary mechanism driving tidal action, explaining two tidal equipotential bulges, and accounting for two high tides per day.

This is the primary mechanism that drives tidal action and explains two equipotential tidal bulges, accounting for two daily high waters.

When the tidal equipotential changes, the ocean surface is no longer aligned with it, so the apparent direction of the vertical shifts.