Comparison of observed downstream-to-upstream proton temperature ratios with CGL predictions. Panels (a) and (b) show the parallel (T_∥d/T_∥u) and perpendicular (T_⊥d/T_⊥u) temperature ratios, respectively, with markers color-coded by shock obliquity. The dashed line denotes the temperature ratio predicted by the CGL double-adiabatic model based on magnetic-field and density compression. Deviations from this line indicate the influence of nonadiabatic and kinetic processes across the shock. Panels (c) and (d) show the relative change in temperature anisotropy, A_d/A_u, as a function of the magnetic compression ratio r_B for quasi-parallel (c) and quasi-perpendicular (d) shocks, respectively.