Simulated K_p − v plots to test varying the argument of periastron ω in ten different test cases. Top: simulations of a ‘clear’ WASP-107 b that has no cloud deck present cross-correlated with a ‘clear’ template that excludes clouds for five different values of ω. Middle: same but now simulating a ‘cloudy’ WASP-107 b cross-correlated with a ‘cloudy’ template, where both the simulation and template include a cloud deck at P = 10⁻⁵ bar. The data are shown using the same colour scale as the test above for comparison. Bottom: same as the middle row but now shown with its own colour scale for reference.