The Earth’s atmospheric flows are powered by gradients of solar heating: vertical gradients cause three-dimensional convection whereas horizontal gradients drive planetary scale planar flows. The question is whether the flows of intermediate scales (which form weather patterns) obtain their energy from a large-scale planar flows or from a small-scale 3D turbulence. The paradox is that planar flows do not transfer energy downscale whereas 3D turbulence does not support an upscale transfer. I’ll review theory, experiments and observations that shed light on this problem.