As we said, the moon controls the tides, but we also said that the sun plays a large role to. Because the earth is constantly revolving around the sun, and the moon around the earth, the moon, earth, and sun, aren't always perfectly in line. During the First and Third Quarter phases of the moon, the ocean acts differently than during the Full and New moon phases. While the moon is in the firts and third quarter phases, it's position is at right angles to that of the sun. So now they are playing a little celestial tug of war. Of course, the oon always wins, and the tides obediently follow, but the sun does weaken the moon's pull, and the range of these tides is a great deal less than usual. These tides are what we call Neap Tides. Some say that there is also a difference between the first and third quarters, but this is not so, as you see in the below graphs, these are both examples of neap tides. Notice the range is veren't large, this you can tell by the slope. The steeper the slope the greater the range.
During the New moon and Full moon phases, the earthm sun, and moon are in line. In this case, the sun actually helps the moon, and adds to the moon's ability to pull the tides. The range is greater, the tides rise higher, and fall lower, than usual. These are what we call Spring Tides. The word Spring, though, comes from the anglosaxin word springan, which means to leap. These tides are also referd to as Leap Tides.
Two times a year, spring tides, or leap tides, are exceptionally high, close to forty percent higher. This is due to a change in the moon's distance from us. The moon is actually 30,000 miles closer than usual, and as we've stated, the closer you are, the greater the gravitational force.
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