Line strength as a function of metallicity for TRAPPIST-1 d, e, f, and g (labeled). We define line strength as the difference between the maximum peak and minimum continuum of the transmission spectrum between 1.1 and 1.7 μm. Each curve shows cloud top pressures according to the color bar. 1σ and 3σ lines show the uncertainty bounds of the model to the HST observations of de Wit et al. (2018). For planet g, we plot the highest reduced χ² we were able to obtain as the line labeled <1σ. Note that planet d has a larger range of line strengths, due to its higher temperature and lower density coupling to give it a significantly larger scale height.