Take for example class E airspace around an airport that extends upwards from 700 feet above the surface (magenta fuzzy colored circle).
Sometimes this airspace does not form a perfect circle around an airport. Oftentimes, one side is extended outwards. Oftentimes, two sides are extended outwards.
I've been told this shape is due to approaches.
However, can't one approach an airport/airspace from any side? Therefore, how do they determine which side of the class E airspace (circle) to extend outwards on a map?
Also, some class E airspace starts at the surface. What, specifically, would cause class E airspace surrounding an airport to begin at the surface? Airports with more traffic...?