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This paper summarizes mapping of an impact of the background atmosphere on a brazed joint formation. The broad range of background atmosphere conditions was considered. Two main parameters include: (i) the oxygen content in the range of 20 ppm to 200,000 ppm, and (ii) the dew point temperature in the range of 225 K to 266 K. The metrics used to evaluate that impact involve multiple joint fillet topographical features. The assessment was performed following detailed brazeability studies of the experimental specimens. The experimental program has involved Controlled Atmosphere Brazing of a wedge-tee brazing sheet mating surface with a variable gap clearance (over the length of 50 mm), to a non-clad AA3003 sheet. Brazing was performed (i) without or (ii) with a coating of the potassium-fluoro-aluminate flux. The tests were performed in a transparent hot zone brazing furnace. The peak brazing temperature in all tests was at the 873 K level, with the ramp-up heating of less than 100 K per minute and a rapid quench in industrial grade Nitrogen.