The phrase "air currents" refers to the movement of air in a certain direction. It's like the flow of wind or breeze in the atmosphere, similar to how water moves in a river. Full definition
The air inside a garden greenhouse is heated because it is enclosed, preventing the circulation of air currents that would carry away heat and cool the interior. (ase.tufts.edu)
It all depends on the fast flowing air currents (jet stream) that the plane flies in. (greenplanet.com)
The leader of a V - shaped flock works the hardest, fighting strong air currents while others save energy by traveling in his wake. (sciencemag.org)