Thermal inertia versus temperature T for grain size R. Left panels: R = 100 μm. Right panels: R = 1 cm, tight contacts (top panels) or loose contacts (bottom panels). The thermal inertia is given for crystalline (full line) or amorphous (dotted line) ice forms for porosities p = 0.26 (black), p = 0.5 (red) and p = 0.84 (orange). The bulk thermal inertias of crystalline (dashed line) and amorphous (dot-dashed line) forms are also plotted. The contribution of radiative conductivity to thermal inertia is also plotted (−...− line).