Last Tuesday, as every Halloween, I re-watched the Cowboy Bebop movie. For those who don't know, it is a sci-fi anime set around the solar system in an hypothetical future.
This question focuses on the "airwalls" that surround the cities on Mars. They seem to be there to keep the atmosphere from escaping the cities by blowing some air up. They are needed because obviously glass domes would be too big and would probably collapse (in addition to being an obstacle to spaceships).
We see one in the distance in the following shot (larger version available by clicking for all following images):
And more upclose here:
How would these "airwalls" be able to maintain a breathable athmosphere within them, while keeping almost space conditions outside, to the point that highways connecting different cities need to be enclosed in tubes?
Since someone asked about the allowed tech level, this is a human society a few hundred years from today. Humanity can travel easily (superluminal speeds) within the solar system and colonize other planets. I would not know how to quantify this "level".