Phase Shift
shift in a wave's position relative to a reference point

The phase of a wave, measured in degrees, where 360 degrees is one wavelength, indicates the current position of the wave relative to a reference position. For example, if at time T1 the position of the wave along the vertical line was:

while at time T2, the position of the wave was:

then the wavelength did not change from T1 to T2, but the wave's position relative to the vertical line changed 1/4 wavelength, or 90 degrees. This change is called a "phase shift".

Terms for using data resources. CD-ROM available.
Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.