8 Tides

Tides written by Pam Holden

Tides are the rise and fall of the sea. Changes in the tide happen along the coasts and in rivers near the sea. High tide is when the water is deeper and comes up high on the shore. Low tide is when the water is shallower and does not come up so far. Tides change because the moon and the sun pull on the oceans and make them rise. The moon pulls more strongly than the sun because it is closer to Earth. High tides happen as the sea rises, and low tides happen as it falls. Most places have two high tides and two low tides every day.

Each month there are two special tides called spring tides. The name has nothing to do with the season spring, but is because the sea rises higher. Spring tides happen when the moon and the sun are in line with Earth and they pull together. Spring tides have a big difference between high tides and low tides— high tides are extra high and low tides are very low.

There are also two tides each month called neap tides, which are the opposite to high tides. Neap tides happen when the moon and the sun are in two different directions and they do not pull together. Neap tides do not rise and fall very much, so they have only a small difference between high tides and low tides.

Sometimes strong winds and storms make tides come up much higher than usual. Sea walls have been built to stop damage from huge waves. Some rivers near coasts have special barriers to stop tidal waves from flowing up the rivers into cities and towns.

Tides are important to people for work and play. Tide times are about an hour later each day, so there are charts to tell when high and low tides will happen. Fishermen need to know the best times to move their boats and to catch fish. Big ships need to move in and out of ports and bays at high tide, when the water is deeper. For swimmers, it is safer when the water is flowing in than when the tide is pulling out. Surfers get a better ride as big waves push them in to shore.