Equatorial transit asymmetry calculations in comparison with WASP-39b data. Top: JWST/NIRSpec PRISM transmission evening (pink) and morning transmission spectrum (green) for WASP-39b. Solid (dashed) lines depict equatorial morning (evening) transmission spectra calculated with the IWF Graz cloud model (red: with Fe and full cloud mass load, ρ_g/ρ_d(z), that are offset to the data and other scenarios for clarity) and for Fe-free cloud scenarios with different cloud mass loads, ρ_g/ρ_d(z), in atmospheric layers where 〈a〉 < 0.1 μm (middle gray: 10⁻³ρ_g/ρ_d(z), dark gray: 10⁻²ρ_g/ρ_d(z), black: 0.1ρ_g/ρ_d(z)). The light gray line depicts the cloud-free case in the upper atmosphere. Bottom: Differences between the evening and morning terminator transmission spectra.