why does one nostril always feel more blocked than the other

so this has bugged me forever and i still don't get it. sometimes both sides are clear, but most of the time one is totally fine and the other feels half closed, like the airflow is half as strong. i can switch sides if i lay on one or the other, but it still seems to happen even when i'm just sitting still. is there some built in system that cycles between them, or is it random? i've never asked anyone because it feels too silly, but i honestly don't know how noses actually work on that level. if someone has the simple explanation i'd love to hear it, because right now it just seems like one of those weird body things that never gets explained.