A to C, Representative time courses of g_st in response to darkness and CO₂ enrichment (A), decreased air humidity (B), and O₃ pulse (C) are given to illustrate the calculation of initial changes in stomatal conductance. D, An example of fitting the kinetics of stomatal closure with exponential function, where α describes the overall stomatal response and γ is the value at which g_st stabilized in response to stimuli. In case the stomatal closure significantly followed an exponential function, maximum stomatal closure rate was calculated as α × β. RH, Relative humidity.