Definition
The portion of an airfoil's total lift produced by higher-than-ambient air pressure pushing upward on the lower surface of the wing. It works in combination with the larger contribution from reduced (negative) pressure above the wing to generate the wing's overall lift.
Plain English
Air striking the underside of the wing pushes up on it. That upward push is one of the two ways a wing produces lift, along with the suction-like pull from lower pressure above the wing.
Context Anchor
Seen in airfoil and lift discussions when explaining how pressure differences around a wing help produce lift.
Derivation
‘Positive pressure’ means air pressure higher than the surrounding (ambient) pressure — ‘positive’ here is relative to the outside air, not ‘good’ or ‘strong.’ ‘Lifting action’ simply describes the upward force this higher pressure produces on the wing.
Why Pilots Care
Recognizing this component of lift helps pilots understand how wing shape and angle of attack directly affect climb performance and stall behavior.
Grounding Statement
Picture the lower side of the wing being pushed upward by air that is pressing harder underneath it.
Intuition Check
Do not read positive as meaning good or safe here. It means pressure that is higher than the reference pressure being compared against.
Example Sentence 1
As the pilot increased the angle of attack, the positive pressure lifting action on the lower wing surface grew, contributing to the additional lift needed for the climb.
Example Sentence 2
As angle of attack increases past the critical value, the positive pressure lifting action is lost when airflow separates from the lower surface.