melodic minor scale
A minor scale that raises both the sixth and seventh degrees when ascending and reverts to natural minor when descending
In Depth
The melodic minor was developed to solve the awkward augmented second in the harmonic minor. By raising both the sixth and seventh degrees in ascending passages, the augmented second is eliminated and the scale moves smoothly to the tonic. When descending, the raised notes are unnecessary (no leading tone needed going down), so the scale reverts to natural minor. In jazz theory, the ascending form is used in both directions and is called the jazz minor scale, forming the basis of several important improvisational modes.
The jazz minor scale's modes include the Lydian dominant (mode 4), used extensively by jazz musicians, and the altered scale (mode 7), used over altered dominant chords.