A♭ Lydian

A♭1B♭2C3D♯4E♭5F6G7

Major with a raised fourth. The fourth mode of the major scale.

The same sounds spelled from the other side are G♯ Lydian.

Written out

Fig. 2 · Ab Lydian, ascending

Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.

A♭WB♭WCWDHE♭WFWGHA♭

A♭ Lydian is A♭, B♭, C, D, E♭, F and G, and back to A♭.

Its steps are W – W – W – H – W – W – H, where W is a whole step and H a half.

On the same tonic, A♭ major differs from it by exactly one note.

Across the first twelve frets of the ukulele its notes fall in 30 places, which is what makes a scale a shape rather than a list.

Found by testing every chord in the catalogue against these 7 sounds, not chosen.