Rhythm is quite simple to understand, Rhythm means movement, which creates interest within a design, if you think of music it's like the beat, there is always an underlying beat that takes us through a song or piece of music and rhythm in design is the same.
There are four main ways of creating rhythm within a design:
The primary purpose of rhythm is to guide the eye to the focal area but without trapping it there.
Transition helps to create greater impact, similar shaped balloons can be graduated in size to add variety and therefore transition within the design, if you think about music again, the transition in music is when it changes from one key to another, so with balloons it can be when we change from one balloon size to another.
So looking at the 'Dolphin Arch' below, the transition in this design is where the balloons are decreasing/graduated in size from the base to the centre.
This design also uses repetition to create rhythm, this has been formed with the use of the 260Q curly spirals in the centre of the design.