This image shows a ripple diagram, showing waves on a graph. A line follows the width of the diagram, which represents the 'mean water level'. On the left, one arrow points upwards and one points downwards to show the 'distance from the mean water level', above and below the mean water level. A wave runs along the line, first peaking above the mean water level, then below. The peaks decrease as the wave runs along the line. At the end of the mean water level line there is a label indicating that this is the 'distance from impact'.