The present invention is directed to a method and apparatus for making nanofiber webs, wherein a source of process air is utilized to affect the spray pattern and quality of fibrillated material expressed from a die assembly including a multi-fluid opening. Appropriately, the aforementioned process air is defined herein as an alternate or ancillary air source apart from primary process air, which primary air is simultaneously supplied with the molten polymeric material to the fiber forming multi-fluid opening. The ancillary air source of the invention is further distinct from secondary air, which is also known in the art as quenching air. The ancillary air can be described as a continuous fluid curtain of shielding or shaping air.