Three-dimensional visualization of the columnar convective modes. Left: snapshot of pressure perturbation (nonaxisymmetric component) from the nonlinear simulation shown as a 3D volume rendering. The red-yellow and blue-cyan parts correspond to the regions with positive and negative pressure perturbations, respectively. Right: eigenfunctions of pressure perturbation of the columnar convective modes extracted from the simulation data using SVD. The cases with m = 2 and m = 12 are shown.