<p>Pattern formation is crucial for controlling fluid motion and spatiotemporal organization in living and synthetic active systems. While pattern formation in miscible fluid systems is typically driven by reaction-diffusion processes or thermal gradients, we show pattern formations in an isothermal miscible fluid system involving simple protein and sugar solutions. Upon introducing a less dense urease solution into higher density glucose or sucrose solutions, the protein initially spreads at the air-water interface, then forms spiral patterns after several minutes. The mechanism involves an interplay between Marangoni effects, evaporation, and airflow. Our work suggests that reaction-diffusion pattern formation can be replicated by replacing the reaction-induced inhomogeneous solute distribution by evaporation-induced inhomogeneity. In both cases, the fast diffusive or Marangoni spreading is counteracted by a slower step that reverses the solute homogenization. These insights enable the manipulation of fluid motion and surface morphology, with implications in coating technologies, materials science, and microfluidics.</p><p></p>