Dennis Mangold of Ten Hills writes, "While listening to my NOAA Weather Radio the other day, when they mentioned predicted wave heights they mentioned a 'dominate period.' What does that mean?" The term is "dominant period," and it refers to the average time, in seconds, between waves with the greatest energy. In body-surfing, it is the time you get to catch your breath and turn around before you get clobbered again. Remember: Weather Radios save lives and make great holiday gifts.