Water Education - A Kid's Guide To Tides
Have you ever taken a swim in the ocean? You may have noticed that the water is lower and higher at certain times during the day. The different water levels are referred to as tides. Tides are basically just the rising and falling level of huge bodies of water. Can you guess what causes tides? The moon affects tides since they are caused by the interaction of gravity between the moon and the Earth. Gravitational attraction is kind of just a fancy word for pull. The pull of the moon causes the ocean to bulge in it's direction. The ocean on the opposite side of the Earth will also have a bulge since the Earth is being pulled away from the water by the moon. The Earth rotates, causing this to happen two times each day, meaning that high tide and low tide occurs twice daily.
Does The Sun Affect Tides?
When the Earth, moon, and sun are all in a line, really strong tides called Spring tides can happen. Spring tides only happen during the new moon and the full moon, when the forces of gravity of both the sun and the moon. There is a special kind of Spring tide called the Proxigean Spring tide . It is a really high tide and happens when there is a new moon that is unusually close to the Earth. The Proxigean Spring tide only happens about once every one and a half years; that's how rare it is. Neap tides are another type of tide. Neap tides are smaller and happen when the sun, Earth, and moon form a right angle. During neap tides, the sun and moon will actually pull the water in opposite directions. Neap tides happen during the quarter and three quarter moon.
High Tides and Low Tides
There can be a big difference in water levels in the ocean between high tide and low tide. The difference between the tides is call the tidal range. In some places, the ocean level can rise and fall by more than fifty feet but in other places it will only rise and fall by a few feet. The size of a tidal range can affect the shoreline in different ways. A big tidal range will mean that a big piece of land will be subjected to the force of waves. A smaller tidal range means that the waves will not have as much of an effect on the shoreline and surrounding land. Another common term you hear when talking about tides is tidal current. Tidal current is when the rise and fall of tides allows water to move in and out of bays, estuaries, and harbors. With a rising tide, water moves into the bay, or harbor, creating what is called a flood current. With a falling tide, the water moves out of the bay or harbor, creating what is called an ebb current.
If you are visiting the ocean, it is important to stay safe when taking a swim. Always make sure you are being supervised by your parents or other adults. Tides can make the water levels change very quickly so it is best to avoid trying to swim while the tides are rising and falling. The ocean can be lots of fun as long as you are careful and make sure to stay safe.
Check out these pages for more information on tides.
- Learn About Tides
- Earth's Oceans: Tides
- How Can The Moon Affect Tides?
- The Rise and Fall of Tides
- Understanding Waves, Tides, and Current
- What Causes High and Low Tide?
Written By: Lynn Taylor