science

King tide

King tide is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand King tide rather than just read about it. In short: A king tide is an especially high spring tide, especially the perigean spring tides which occur three or four times a year. King tide is not a scientific term, nor is it used in a scientific context.

Key takeaways

King tide belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect King tide to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of King tide from memory before moving on to harder problems.

Reference excerpt

A king tide is an especially high spring tide, especially the perigean spring tides which occur three or four times a year. King tide is not a scientific term, nor is it used in a scientific context. The expression originated in Pacific countries to describe especially high tides that occur a few times per year. It is now used in North America as well, particularly in low-lying South Florida, where king tides can cause tidal flooding. In Vancouver, Canada, king tides are a growing problem along its seawall.

Definition King tides are the highest tides. They are naturally occurring, predictable events. Tides are the movement of water across Earth's surface caused by the combined effects of the gravitational forces exerted by the Moon, Sun, and the rotation of Earth which manifest in the local rise and fall of sea levels. Tides are driven by the relative positions of the Earth, Sun, Moon, land formations, and relative location on Earth. In the lunar month, the highest tides occur roughly every 14 days, at the new and full moons, when the gravitational pull of the Moon and the Sun are in alignment. These highest tides in the lunar cycle are called spring tides. The proximity of the Moon in relation to Earth and Earth in relation to the Sun also has an effect on tidal ranges. The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete. The gravitational force is greatest when the Moon is at perigee (closest to Earth) and smallest when it is at apogee (farthest from Earth). The Moon has a larger effect on the tides than the Sun, but the Sun's position also has an influence on the tides. Earth moves around the Sun in an elliptic orbit that takes a little over 365 days to complete. Its gravitational force is greatest when the Earth is at perihelion – closest to the Sun in early January – and least when the Earth is at aphelion – farthest from the Sun in early July. The king tides occur at new and full moon when the Earth, Moon and Sun are aligned at perigee and perihelion, resulting in the largest tidal range seen over the course of a year. So, tides are enhanced when the Earth is closest to the Sun around January 2 of each year. They are reduced when it is furthest from the Sun, around July 2. The predicted heights of a king tide can be further augmented by local weather patterns and ocean conditions.

References

General references tidesandcurrents.noaa.gov

Inline citations

External links EPA King Tides Factsheet EPA page on king tides and climate change oceanservice.noaa.gov – NOAA National Ocean Service NOAA tool for predicting tide events – Tides and water levels – NOAA tides tutorial King tides photo initiative – North Carolina, US King tides photo initiative – Washington State, US King tides photo initiative – Oregon, US King tides photo initiative – Long Island Sound, US King tides photo initiative – Barnegat Bay, US King tides photo initiative – Australia King tides photo initiative – New South Wales, Australia www.thesinkingoftuvalu.com – King Tide / The Sinking of Tuvalu King tides photo initiative – Hawaii and Pacific Islands King Tides Project

Illustrations

Worked examples

Example 1 — a first encounter with King tide

Start with the simplest possible case. Write down what King tide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to King tide before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about King tide ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of King tide

In research: King tide appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses King tide in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: King tide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Tides, so understanding it makes those chapters shorter.
In everyday life: Look for King tide outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study King tide in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what King tide means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain King tide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is King tide in simple terms?

A king tide is an especially high spring tide, especially the perigean spring tides which occur three or four times a year. King tide is not a scientific term, nor is it used in a scientific context.

Why does King tide matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study King tide?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on King tide.