Does gravity act on gases?

Yes it does! Anything that has mass will have to experience gravity. Now the question is why do gas molecules not have a downward motion individually? That is because there are millions of gas molecules surrounding the considered molecule. read more

They are spherical mainly because the gases are being pulled as a whole by gravity towards the center of the sphere. The atmosphere is another example. We get winds and cyclones, but at the same time, the air envelope does not fly off!! It remains there. Hence gravity acts on gases but influences them as a whole. read more

Yes, gases just like all other materials have density. This is why a balloon filled with helium will rise to the ceiling. It floats because all of the air around it is denser than the helium in the balloon. If you let the helium balloon go outside, it will rise to an altitude that is equal in density as the helium. read more

After ascending to certain height due to thermal energy of expansion caused by the Sun's heating it and its own KE of collisions among other gas molecules, equilibrium is established between the said two forces . Moons Gravity also contributes to the ascent of the gases molecules against Earth's G. read more