Top panel: All-sky display of the observed H I column density distributions, integrating over a velocity range − 8 < v_LSR < 8 km s⁻¹ and distinguishing contributions from the CNM (left), LNM (middle), and WNM (right). The color scale is logarithmic, lg (N_H ∕[cm⁻²]). Bottom panel: H I phase fractions f_CNM (left), f_LNM (middle), and f_WNM (right) for the same data. Galactic coordinates are used, the Galactic Center is in the middle.