atla-annotated:

Korra and Airbending

Korra had a hard time mastering airbending in season one and Tenzin even mentions that she has not mastered real airbending, but only, as he puts it “Korra style airbending”. 

So, when Korra wakes up on that beach after she’s been swallowed by the green glowing Dark Spirit, and her first instinct is to airbend, what exactly does that mean?

There are two possibilities:

Airbending is connected to the spiritual aspect of being the Avatar.

It could simply be that the contact with the spirit connected her to the Spirit World and the airbending happened due to that connection.

Another (not mutually exclusive) option is that the contact with the spirit took some of her bending.

Korra’s first choice of bending has never been air. She does seem to favor fire and water. 

The spirit glowed green. (And as I’ve pointed out here: I think all Dark Spirits are part of the Avatar Spirit) Green is the color of earth. Did the spirit take her earthbending and the airbending happened as a result of that loss?