Hi, I'm currently learning about simple fluid mechanics at university and I fall into a problem I couldn't solve but this isn't the point here. This problem made me realize that if for example you drive a car and inside your car you have a hydrogen filled toy balloon, if you accelerate forward then maybe a bit counter-intuitively the balloon will go forward and might bother you when driving. I thought a bit more about it and now I realize that more the fluid has inertia (density I'd say), the less it will move compared to a fluid that has a lower density (if the fluids are under the action of a force/acceleration). I don't know how to explain this well in English so I understand you if you don't understand what I'm trying to say. Nevertheless, here is my question : as Earth has an acceleration (centripetal one), its atmosphere should suffer changes during the day. There should be a larger quantity of atmosphere during the night since during the night, Earth's surface is opposed to the centripetal acceleration caused by the sun. But Earth's also hasn't a "simple" motion since it rotates on itself inclined with respect to its orbit. So I guess that it could also be possible to have a large amount of atmosphere during the day, but I'm unsure. Is this particularity really happening? If you didn't understand anything, please let me know and I'll explain it in a better way.