In terms of the graphs, it refers to the height of the tallest peak in a planetary waveform pattern. In experiential terms, it describes the intensity of the astrological influences present at a given time. Wave phenomena appear in many areas of study, including mathematics, science and music. The strength or intensity of these waves are described by the distance between the peaks and the valleys in the wave.
Larger distances indicate a more powerful phenomenon.
The light is brighter, the sound waves are louder, the earthquakes topple more buildings, the stock market is more volatile, etc. In astrology, the effects of the planetary influences on our lives and behavior are more marked when the waves are bigger. The world feels more hurried, demanding, intense and out of control. In particular, the height of the tallest peak is taken to be the strength of the entire waveform. The zodiacal position and height in units of this tallest peak are printed at the bottom of each graph.