How does tide work

But that's not as noticeable as what happens in the ocean. Anything in the universe that has mass also has its own gravitational field. Sometimes, in the case of humans, that gravitational field is so tiny that they're irrelevant to our everyday lives. But when the mass starts increasing, changes start to take place. The Earth, for example, has enough of a gravitational field to keep things on the ground, and to keep the Moon rotating around the planet.

The Moon, in turn has its own gravitational field. This field is strong enough to create a tug on the Earth's oceans, and because the Moon is in rotation around the Earth, the strength of this tug varies by location and time of day. The Moon is mostly responsible for high tide, when there's more water in areas, and low tide, when there's less.

The Moon is the biggest player in creating tides, but it's not the only planetary body involved. There's also the body with the biggest gravitational pull in the solar system, the Sun. Even though its closeness to Earth means the Moon has the bigger impact, the Sun's affect on tides is noticeable.

During new, or full, moons, the Earth, Moon, and Sun are all in alignment. That alignment allows all of those gravitational forces to join together, creating stronger tides known as spring tides. At the sublunar point and the antipodal point, the moon's gravitational pull lacks a horizontal component — something that is also missing at the two corners of the world that are located 90 degrees away from these spots. Those four areas are unique in that regard; every other location on Earth experiences a horizontal force that pushes water molecules in the ocean toward either the sublunar point where the moon's gravitational force is at its strongest or the antipodal point where the moon's gravitational pull is at its weakest.

This is why the ocean bulges up over those two areas. Once every 24 hours, Earth completes a full rotation around its axis. During this process, any given spot on the planet's surface like, say, Long Island or Australia will pass right through both of those ocean bulges. So — in most areas — when your home is directly under a bulge, the local tide should be high. But as it enters the space between the bulges, the tide in your area should get lower.

This isn't always the case, as you'll learn next. For now, let's discuss another factor that influences our tides. The sun also exerts a gravitational pull on the oceans , but because our solar companion is further away, its effects on the tides are less pronounced than the moon's.

Still, the big ball of gas and plasma does noticeably enhance tidal bulges on a regular basis. He notes that this happens during two separate lunar phases: Full moons and new moons. Astronomers and Earth scientists refer to these plus-sized tides as spring tides. Note that the name has nothing to do with the spring season; indeed, spring tides occur throughout the year.

During spring tides, the "high" tides are really high and the "low" tides are unusually low. Things get less extreme when the sun and moon sit at right angles to each other relative to Earth. Such an arrangement will produce a neap tide; a period in which the difference between high and low tides is minimal. Brace yourself: Things are about to get even more complex. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. Marine ecosystems contain a diverse array of living organisms and abiotic processes. From massive marine mammals like whales to the tiny krill that form the bottom of the food chain, all life in the ocean is interconnected.

While the ocean seems vast and unending, it is, in fact, finite; as the climate continues to change, we are learning more about those limits. Explore these resources to teach students about marine organisms, their relationship with one another, and with their environment. Along coasts, the water slowly rises up over the shore and then slowly falls back again. The Earth's rotation and the gravitational pull of the sun and moon create tides.

The intertidal zone is an ecosystem found on marine shorelines, where a multitude of organisms living on the shore survive changes between high and low tides. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. The water moving away from the moon resists the gravitational forces that attempt to pull it in the opposite direction.

Because the gravitational pull of the moon is weaker on the far side of the Earth, inertia wins, the ocean bulges out and high tide occurs. As the Earth spins, different areas of the planet face the moon, and this rotation causes the tides to cycle around the planet. NOS scientists advanced tidal recording systems as well as satellite imagery to monitor tides and water levels. These data are used to predict ocean behavior in order to protect our coasts and coastal communities.