An air cooled condenser fin comprises flow channel walls defining an air flow channel. The flow channel walls include planar sections separated by intermittent flow interruptions which are spaced apart along the air flow channel. The intermittent flow interruptions are defined by the flow channel walls. The intermittent flow interruptions may for example comprise splits formed by a staggered arrangement in which the planar sections of the flow channel walls before and after each split are staggered; or intermittent sinusoidal waves formed into the flow channel walls; or louvers formed into the flow channel walls to create openings passing through the flow channel walls at the louvers. The intermittent flow interruptions may be spaced apart along the air flow channel by at least 5 hydraulic diameters, and in some embodiments by 5-10 hydraulic diameters. A plurality of such air cooled condenser fins are suitably employed with the air flow channels arranged in parallel.