NOT FOR NAVIGATION
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Both the author and the website provider assume no liability for damages arising from the use of these predictions. They are not certified to be correct, and they do not incorporate the effects of tropical storms, El Niño, seismic events, continental drift, or changes in global sea level. Tides are when sea level rises and falls due to the combined effects of forces of gravity exerted by the Moon and the Sun and also the rotation of the Earth.
The Ocean Isle Beach area experiences four tides a day, two high and two low each day. While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surges, especially in shallow seas and near coasts.
Tides are mostly semi-diurnal (meaning two high waters & two low waters each day), or diurnal (meaning one tidal cycle per day). The two high tides on a given day are normally not the same height – these are the higher high water and the lower high water in tide tables. The two low waters each day are the higher low water and the lower low water.
Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores. The following pages describe the tremendous forces that cause the world’s tides, and why it is important for us to understand how they work.
Basically, tides are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. They originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea surface. When the highest part, or crest of the wave reaches a particular location, high tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high and the low tide is called the tidal range.
A horizontal movement of water often accompanies the rising and falling of the tide. This is called the tidal current. The incoming tide along the coast and into the bays and estuaries is called a flood current; the outgoing is called an ebb current. The strongest flood and ebb currents usually occur before or near the time of the high and low. The weakest currents occur between the flood and ebb currents and are called slack. In the open ocean tidal currents are relatively weak. Near estuary entrances, narrow straits and inlets, the speed of tidal currents can reach up to several kilometers per hour