Main panels: Merger and fragmentation rates as a function of pressure contrast between the cloud and the interface (left) and Δ₁₀ (right). Top panels: Difference between merger and fragmentation rates. A strong trend with pressure contrast can be seen, with under-pressurized clouds being more likely to undergo a fragmentation event as opposed to a merger. The trend with Δ₁₀ is weaker – clouds with a very small (large) number of neighbors are likely to fragment (merge), while the net rate is largely flat for intermediate values of Δ₁₀.