A shortwave trough can be defined in several ways. The following are characteristics that most shortwave troughs possess:
(1) Shortwaves are smaller than longwave troughs
(2) Shortwaves have a counterclockwise kink to the height contours
(3) They are associated with an upper level front or a cold pool aloft
(4) Shortwaves generate positive curvature vorticity and positive shear vorticity
(5) Shortwaves often represent baroclinicity in the troposphere (WAA and CAA)
(6) Shortwaves are imbedded within the longwave trough / ridge pattern
(7) Shortwaves are best located on the 700 and 500 mb chart / prog
(8) Rising motion occurs within the exit sector of a shortwave
(9) Their size and influence ranges from the mesoscale to the synoptic scale
(10) Shortwaves move faster than longwaves (usually more than twice as fast).
The link below has examples of shortwave troughs.