The image below is an example of rhythm. It illustrates a specific pattern and tells your mind which way the picture is headed.
Raymond, Patrick. "Patrick Raymond-The Rhythm Series- Art for Professionals." Patrick Raymond-The Rhythm Series- Art for Professionals. N.p., 01 Jan. 2012. Web. 27 Nov. 2012. <http://art.patrickraymond.com/Rhythm/rhythm.htm>
The image below is a totally different example of rhythm but follows the same concept. This form can also be called manipulating rhythm.
The final example of rhythm illustrates a form of a pattern heading in a particular direction. As you can see all the shapes are parallel and aligned to one another. There is a term for this called Progressive Rhythm.