Diurnal phase shift

Note 1: The major changes usually occur during the period of time when sunrise or sunset is present at critical points along the path.

Note 2: Significant phase shifts may occur on paths wherein a reflection area of the path is subject to a large tidal range.

Note 3: In cable systems, significant phase shifts can be occasioned by diurnal temperature variance.

Source: from Federal Standard 1037C and from MIL-STD-188