A neap tide—seven days after a spring tide—refers to a period of moderate tides when the sun and moon are at right angles to each other. A spring tide is a common historical term that has nothing to do with the season of spring.

*Spring tides occur during the full moon and the new moon. During the moon’s quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide. Neap tides are especially weak tides.

Neap tides

Dangers associated with King Tides Spring tides are more extreme than neap tides. During a spring tide, high tide will bring the water much further up the beach than normal. Sometimes, the water will extend even up past the beach. Ocean currents are stronger during spring tides, so use caution when swimming.

You can tell if the tide is coming in or out by reading a local tide table since they list the predicted times that the tide will be highest and lowest. In the time that the tide shifts from its lowest point to its highest point, the tide comes in. The tide goes out during the other time intervals.

Tide and Surfing If the tide is too high and rising, each successive wave will push higher, while if the tide is high and falling, the energy in the waves will decrease with each wave. As the tide approaches low tide, the waves will be less powerful and flat.

When low tide is expressed as a negative (-), it means the tide will fall below Chart Datum. For example, -1 means the low tide will be 1 foot (0.30 m) below the average low water mark. The low tide may also be a positive number. The number 1.5 indicates that the lowest tide will be 1.5 feet (0.46 m) above Chart Datum.

What tide conditions are best for you? For swimmers, the water is safest during a slack tide, during which the water moves very little. A slack tide happens in the hour preceding or following a high or low tide. Swimmers will also enjoy waves with shorter intervals, which are calmer and less dangerous.

A tide range of 16.6 m (54 ft 6 in) was recorded at springs in Leaf Basin in Ungava Bay, Quebec, Canada in 1953.

When the moon is closer to Earth, the ‘gravitational’ bulge is larger than when the moon is farther from Earth. Therefore, when a given location on Earth makes one revolution in a 24 hour period it experiences one high tide that is higher than the other and one lower low tide.

Because the Earth rotates through two tidal “bulges” every lunar day, coastal areas experience two high and two low tides every 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.

Earth’s rotation and the gravitational pull of the sun and moon create tides on our planet. Because the sun is so much larger than the moon (27 million times more masssive), it has a much bigger graviational pull on Earth. As the ocean bulges toward the moon, a high tide is created.

Thus, tides are draining energy out of Earth’s rotation, slowing it down. Because of this loss of rotational energy in about a billion years or so Earth will rotate at the same rate that the Moon orbits it.

The URI scientists’ observations showed that the Earth’s rotation modifies internal waves as they travel cross the deep basin. This effect mainly influences the internal waves that form on the 24-hour period of diurnal tides, dispersing the energy and inhibiting the steepening process.

Gravity is one major force that creates tides. In 1687, Sir Isaac Newton explained that ocean tides result from the gravitational attraction of the sun and moon on the oceans of the earth (Sumich, J.L., 1996).

The moon is a major influence on the Earth’s tides, but the sun also generates considerable tidal forces.

An efficient way of guesstimating how much water there is, at any given time of day, over a particular point. The rule of twelfths works like this; take the difference in height between the high and low tide on that day, and divide that by 12 equal chunks.

Smaller bodies of water, like lakes and pools, don’t have noticeable tidal bulges because they lack enough liquid to create pressure that can visibly overcome the pull of Earth’s gravity. The sun’s gravity also affects the tides, accounting for roughly one-third of the phenomenon.

Some bodies of water (the Mediterranean, Baltic, Black Sea, Caspian Sea, and Caribbean) don’t respond strongly to tidal forces. The reasons for this are a bit complex but basically it is due to their size and geographic nature. These areas are described as Non-Tidal.