A
shortwave or
shortwave trough is an embedded kink in the
trough /
ridge pattern. Its length scale is much smaller than that of
longwaves, which are responsible for
synoptic scale systems, although shortwaves may be contained within or found ahead of longwaves and range from the
mesoscale to the synoptic scale. Shortwaves are most frequently caused by either a cold pool or an upper level
front.