Squall lines are convective storms which organize into a linear or bowed structure.
This frame shows an RHI through the above squall line's stratiform region. The reflectivity is characteristically uniform. The horizontal line at about 4 km is the bright band , located 500-1000 m below the melting level. These two frames show the convective, transition and beginning of the stratiform region of a New Mexico summer season squall line, in RHI cross-section scanning mode. The system is moving away from the radar.