This figure represents an average height of the highest one-third of the waves in a given time period -LRB- usually chosen somewhere in the range from NUMBER@1 minutes to twelve hours -RRB- , or in a specific wave or storm system .

This figure represents the average height of the highest one-third of the waves in a given time period -LRB- usually twelve hours -RRB- or in a specific wave or storm system .
