Temporal evolution of the Hα synthetic spectral profiles in λt diagrams for the EB (left panel) and the connected spicule (right panel). The EB and spicule spectra are calculated along the columns A and B marked by the dashed lines in Fig. 1. The blue arrow indicates the spectral profile corresponding to the timeframe presented in Fig. 1. The EB’s beginning is marked by time t = 0, corresponding to 290 s in the simulation of MS20.