Supplement Number 1

The supplementary material contains Four figures: Fig. S1 supplements the "Bubble trajectory and deformation" section by clarifying the time intervals for bubble trajectory superimposition. Fig. S2 supplements this same section through quantitative analysis of trajectory amplitude variations as bubbles rise in heavy and light layers. Fig. S3 supplements the "Bubble velocity" section to assist in explaining the change in bubble velocity through the deformation of the bubble. Fig. S4 supplements the explanation of the experimental setup for the density-stratified fluid environment.