This site says that the tropopause is at a higher altitude at the equator because:
Gravitational force from a point is higher closer to it and reduces with increasing distance from it. Because the Earth itself is broader at equator, the equator experiences less gravity allowing air to reach bigger heights. Poles are closer to gravitational center and experience higher gravity.
Earth is rotating at a rate of 24 hours per spin. Not just the ground, but also the atmosphere is spinning with it. The gas molecules at poles are closer to this rotational axis while those near the equator are farther away on a larger radius. Therefore, air at equator experience a greater centrifugal force and moves farther away from Earth.
Earth's orientation in space allows equator to be more closer to the Sun. Due to this higher gravity, atmosphere deforms slightly towards the sun while draining a bit more air from the poles.
Regions near equator receives more sunlight than the poles making them hotter and less air dense. So equatorial gases reaches greater heights to exert the same pressure as at the poles.
Tidal effect by the moon Just like the tides, Moon's gravity causes the atmosphere to deform. Since the moon orbits close to the equator, equatorial thickness is increased.
These all seem like plausible factors, but I'm not sure what the main reasons are. Which factors contribute the most, and how much?
To me reasons 1, 2 and 4 seem like the main causes. Do tidal forces really matter? Does distance to the Sun really matter? (Seems ridiculous because the Sun is 150 million kilometers away from Earth, so a few extra thousand kilometers shouldn't matter at all)
Is there any main biggest factor that makes much more of a difference than the other factors?