What you need to know about the tides

August 30, 2019, 1:25 p.m.

When we talk about tides, most of us think it's when the ocean is higher or lower on the beach. But there's so much more to know.

For starters, high tide is actually the crest of a really long wave. The highest tides in the world are found at the Bay of Fundy in Nova Scotia, where they have a range of 44.6 feet, but it's the same process happening everywhere.

NOAA explains it best:

"Tides are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. Tides 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 tide and the low tide is called the tidal range."

The moon's gravitational pull causes the tides, but the sun's gravitational pull also plays a role. The sun's gravitational force is only about 46% of the moon's, which means its pull on Earth's oceans is smaller and so too is its effect on the tides. When the moon, the sun and Earth are aligned, the pull of the sun adds to the pull of the moon and causes extreme tides — or, extra long waves.

This relationship also comes into play when we talk about king tides, a topic that comes up when a storm is on the horizon. King tides are simply an unscientific term used to describe really high tides. When the moon is closest to Earth — a state called perigee — and this coincides with a full or a new moon, this pushes the tidal range slightly higher.

And when you throw a tropical storm or hurricane into the mix, things really get interesting because a storm system actually pushes more water ahead of it before it even makes landfall. Case in point, as Hurricane Dorian gets closer to the Florida coast, the tides become a bigger factor in how much damage is possible.

"The fact that this storm is hitting during some of the highest tides of the year is very concerning," CNN meteorologist Brandon Miller said. "The King Tides adding a couple of feet to the water height is almost like the storm being a category higher on scale."

Editor's note: This story has been updated since it was published in August 2015.