I am posing this question from the perspective of a novice. I read an article, from Scientific American, titled "No One Can Explain Why Planes Stay in the Air". The article explains how, while we understand how to create flight (with airplanes, for example), we still don't understand why there is lower pressure above the wing, allowing for the air above the wing to flow more quickly, thus generating lift. If you care about this topic, read the article I am referencing, it lays out the two competing theories for explaining why air pressure is lower above an airplane wing in flight. It also shows how both of the theories are incomplete.
I found it fascinating that we still don't understand this, so I decided to think about it a little. I am not a physicist, but I would say I have a basic understand of physics (having at least studied it during high school). The first aspect of what is going on when an airplane is flying that I decided to think about is (to me) the most obvious force involved in flight: gravity. I then conjured up the question, "how does gravity act on air?" If you type that into a google search, it will bring up this text box at the top:
As gravity hugs the blanket of air to the Earth's surface, what physicists call a density gradient is set up in the air. The air near the ground is pulled on by gravity and compressed by the air higher in the sky. This causes the air near the ground to be denser and at a greater pressure than air at higher elevations.
Google cites this as coming from https://www.uu.edu/dept/physics/scienceguys/2001Oct.cfm - I am assuming it is reputable if google is choosing to present it as a "quick answer" (if you will) for the search "does gravity act on air".
In this explanation, I think what it is saying is, the air that is closer to the ground is more closely packed together. It mentions the "density gradient," and I interpret that concept to mean that, as you get closer to the edge of our atmosphere (starting at ground level), the air will become less and less dense as you go higher and higher. So if that is how air behaves under gravity, and an airplane is flying through the air, this means that, as it is being propelled sideways (as it's wings "cut through the air"), by nature, it is going to split the density gradient of the air (which I think can also be directly linked to air pressure - more dense air, air closer to the ground, is higher pressure, and less dense air, air further from the ground, is lower pressure). In saying this, then I think I can say that, as the wing cuts through the air, there is no reason why it wouldn't cut through the air in a way where it creates a situation around the wing, where there is lower pressure above the wing, and higher pressure below the wing (even if it is only a small difference - much force is being applied sideways in this situation by the airplane), thus allowing for lift. There is no reason for the air that is higher up (the inherently less dense air) to pass below the wing, because it is already above the more dense air (the air that is already closer to the ground) as described by the density gradient. It seems to me, that this notion supports the idea that there would be lower pressure above an airplane wing (allowing for the air to move more quickly above the wing), and higher pressure below it. Everything I have said kind of seems pretty obvious, and seems to support the idea that lift will be inherent in any situation where something is slicing horizontally through the air at a rate of speed where it is able to negate any other forces that may act in an effort to make it move non-horizontally. I'm guessing I am missing something, and it isn't this (seemingly) simple - either way, with what I think I have discovered through my brief research, I basically want to know why what I said is wrong, if it is (I guess it would be pretty cool if I just figured out this problem haha).