Light curves for the simulations of four group I models, with loops in an initial cool state (Table 1). In this case, the length L of the loop’s central part increases from 0.5 Mm to 5.5 Mm. The intensities correspond to four AIA channels (left column), five SPICE lines (right column), and HRIEUV (on the right axis of all subfigures). For better visibility, the intensity of the C III line is divided by 10. Results are presented between t = 90 and 200 s, with the start (t = 100 s) and the end times (t = 110 s) of the impulsive heating indicated by two vertical dotted lines.