Detailed cutouts showing the evolution of Hα from t = 2.8 min to t = 5.13 min with 28.2 seconds cadence where the chromospheric jet appears in different wavelength positions, which are indicated within the panels of the first column. The second but last and last row correspond to the LOS velocity based on the Centre of Gravity (COG) method and the FWHM, respectively. The blue contours mark the region of the dark feature at the line position Δλ = −900 mÅ.