Harmonic development can be very insistent, moving swiftly from one key to another within a few chords. Or, it may languish between two or three ambiguous harmonies for quite some time. The degree of harmonic urgency primarily results from the relative strength of chord-root relationships and the length of time between chord changes (harmonic rhythm). Imagine the animation above as a graph of a series of chords moving at various levels of tension and relaxation in real time--Try to imagine the sounds of the harmonies!
Perhaps the most succinct developmental device--a microcosm of developmental harmony--is the short progression of chords used by jazz players to move from one part of the composition to another, the turnaround. Turnarounds, as strong directional pointers, most often occur at the end of a composition (before its improvised repetition), at the end of a section, or even at the end of a phrase. Example 1, below, depicts the end of one section (in the key of F major) and the beginning of another (in A minor) smoothed over by the turnaround chords (circled ) which typically are the ii and V chords of the new section's key. Turnaround chords are often indicated by the chord symbols of the composition but can also be improvisationally inserted by the player to provide more specific direction to the form.