Comparison between the theoretical and observed total turbulence energy, perpendicular turbulence energy and slab turbulence energy, and the ratio between the perpendicular and slab turbulence energy as a function of the heliocentric distance for the slow and fast solar wind. Figures A1/B1, A2/B2, A3/B3, and A4/B4 show the energy in forward propagating modes, the energy in backward propagating modes, the fluctuating magnetic energy, and the fluctuating kinetic energy. Figures a1/b1, a2/b2, a3/b3, and a4/b4 show the corresponding ratios between the perpendicular and slab turbulence energy. The solid and dashed curves show the theoretical results, and the scatter plots with error bars show the observed results. See the text for details. (a) Slow solar wind. (b) Fast solar wind.