Possible discharges in the atmosphere of HAT-P7b on the nightside (top) and at the morning terminator (bottom). Top panels: degree of ionisation, f_e, and the dust number density per hydrogen, n_d∕n_H. Bottom panels: ratio of electron number density, n_e, to the number of cloud particles, n_d. For n_e ∕n_d > 1, the atmosphere is in the electron dominated regime. The dotted vertical line represents p_gas = 5.56 × 10⁻⁴ bar, the pressurelimit below which electric field breakdown may occur. To the left of this line, the clouds are susceptible to large-scale discharges.