Harmonic minor · The minor scales · Music theory
Natural minor lacks a leading tone: its degree VII lies a whole step below the tonic (it is called the subtonic). Harmonic minor raises VII a half step (in…
Harmonic minor
Natural minor lacks a leading tone: its degree VII lies a whole step below the tonic (it is called the subtonic). Harmonic minor raises VII a half step (in A minor, G♯) and turns it into a leading tone, as in major; with it the dominant chord is major.
Between VI and VII this leaves an augmented 2nd (F–G♯), the most characteristic turn of this scale. It is the scale of harmony in the minor mode, the one the checker uses: the key signature plus the leading tone.
The intervals proper to the harmonic form
Raising VII creates intervals that do not exist among the notes of the major scale: an augmented 2nd (VI–VII), an augmented 5th (III–VII), a diminished 7th (VII–VI) and a new augmented 4th (IV–VII). Recognizing them lets you identify the scale at a glance, and exams often ask about them.
In a classical melody those leaps are handled with care: the augmented 2nd sounds very characteristic, almost oriental, and that is why the melodic form exists.