Why Atmosphere is Thicker at Equator

Atmosphere is the layer of gases that surrounds the Earth retained by Earth's gravity. Have you ever come across the question; what is the shape of the atmosphere?

It's fair to think that the atmosphere is shaped somewhat like the Earth itself. because of gravity. We know that the Earth is not a perfect sphere. So, We can assume atmosphere to have a similar shape. But amazingly, the shape of the Atmosphere is affected by a lot of factors and the deformation is even more. Lets see why that is..

Factors Affecting The Shape of Atmosphere

1. 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.


2. 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.


3. 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.


4. 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

5. Just like the tides, Moon's gravity causes the atmosphere to deform. Since the moon orbits close to the equator, equatorial thickness is increased.

Thicker at Equator, Thinner at Poles and Even more Deformed

The shape of atmosphere is highly dynamic and is affected by many factors. Recent gravity maps of our planet shows that Earth's gravity is not uniformly distributed. Its shape is probably deformed by Solar winds as well. Earths surface temperature distribution is uneven owing to the geography, oceans, vegetation and so on. This is likely to give rise to various atmospheric circulation patterns, which may affect te overall shape as well. But, using the above facts, we can have a rough idea about the real distribution of the atmosphere. Extending these, we predict the possibility for the following phenomena to take place as a bonus :D

Possible Effects 

• Air is denser than vacuum. So, this shape can exhibit a lens effect; More sunlight tend to converge around the equator rather than the poles.
• Ozone layer is more thinner near the poles. (Fact: Ozone hole is worst over the Antarctica* but it turned out that this isn't true. Ozone layer is infact thicker at temperate zones! which is explained in terms of atmospheric circulation [see comments])
• Equators experience more greenhouse effect.