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Home  Education  Tides and Water Levels  Frequency of Tides - The Lunar Day
  << Back Unlike a 24-hour solar  day, a lunar day lasts 24 hours and 50 minutes. This occurs because the  moon revolves around the Earth in the same direction that the Earth is  rotating on its axis. Therefore, it takes the Earth an extra 50 minutes  to “catch up” to the moon. Since the Earth rotates through two tidal  “bulges” every lunar day, we experience two high and two low tides  every 24 hours and 50 minutes. Here, we see the relationship between  the tidal cycle and the lunar day. High tides occur 12 hours and 25  minutes apart, taking six hours and 12.5 minutes for the water at the  shore to go from high to low, and then from low to high.


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