Left panel: synthetic transit spectra, observations, and synthetic observations for the planet TrES-4b. Black crosses denote the ground-based observational data by Chan et al. (2011), Sozzetti et al. (2015), Turner et al. (2016). Black squares denote the HST WFC3 data by Ranjan et al. (2014). Synthetic spectra for the homogeneously cloudy models with X_max = 3 × 10^-4Z_Pl are shown as teal and red solid lines for the DHS and Mie opacity, respectively. The dashed box at ~10 μm highlights the silicates features due to Mg₂SiO₄ resonances.The teal and red dots show the corresponding synthetic observations derived for one and ten transits, re-binned to a resolution of 50. Vertical offsets have been applied for the sake of clarity. Right panel: p values of the Kolmogorov-Smirnov test of the residuals between the synthetic observation of the TrES-4b DHS model and the Mie model (solid teal line). The p value is shown as a function of N_transit for data taken with MIRI LRS considering only the wavelength range of the silicate feature (9–13 μm) and correcting for global model offsets. The dashed teal line shows the p value obtained when analyzing the residuals of the DHS model to its own observation. The black dashed line denotes our threshold value of 10^-3.