Tommy Allsup performs during Friday evening's sock hop at the Surf Ballroom at Clear Lake. (Globe Gazette photo by Matt Foy) Dion DiMucci, whose claim of a coin toss with the late Ritchie Valens has fueled anger in some rock and roll corners.
In Maine (U.S.) low tide occurs roughly at moonrise and high tide with a high moon, corresponding to the simple gravity model of two tidal bulges; at most places however, moon and tides have a phase shift. mixed tide; two uneven tides a day, or one high and one low, is also possible. Tides vary on timescales ranging from hours to years due to a number of factors. To make accurate records, tide gauges at fixed stations measure the water level over time.
Semi-Diurnal tides. A semi-diurnal tide occurs generally when there are two high waters (tides) and two low waters (tides) per day. Typically the time between each successive high or low tide is 12 hours 25 minutes, this is half of one lunar day. Semi-Diurnal tide cycle, with 2 high tides and 2 low tides each day. Copyright Marine Science of Australia, all rights reserved.