Questions tagged [tides]

Tides are the periodic fall and rise of sea-level due to gravitational forces of the moon, sun or earth-rotation. When asking questions specifically about tides, use this tag and also include the [ocean], [moon], [sun] or [earth-rotation] tag if appropriate.

Filter by
Sorted by
Tagged with
20 votes
1 answer
295 views

What can we learn by studying lunar atmospheric tides?

Lunar atmospheric tides are likely insignificant for weather, although Guoqing (2005) asserts that The lunar revolution around the earth strongly influences the atmospheric circulation. They don't ...
gerrit's user avatar
  • 11.7k
18 votes
1 answer
2k views

What influences tide-height the most? Can I guess the height by looking on a globe?

I hope that the question title is resonably clear: What are the most significant factors which influence the tide height? I'm aware of the following couple of them: Sun-Earth-Moon relative position (...
yo''s user avatar
  • 1,158
15 votes
2 answers
553 views

Why is there a daily inequality for low tides?

I understand why there is a daily inequality for high tides. What I do not understand is why the low tides are not equal. The data all seems to be somewhere along the lines of but the theory seems to ...
user avatar
14 votes
2 answers
23k views

Why do high tides occur simultaneously on opposite sides of the Earth?

Most explanations for high tides say high tides come from water being attracted by the moon (2/3) and the sun (1/3). Attraction occurring in the direction of the moon is visible on the side close to ...
mins's user avatar
  • 243
14 votes
3 answers
6k views

How will sea level rise be distributed across the globe?

Sea level rise from melting glaciers will not be uniformly distributed across the globe. However, it isn't clear to me what places will have the most and least extreme changes in sea level rise. I ...
f.thorpe's user avatar
  • 13.5k
12 votes
1 answer
403 views

What is the area with the largest velocity vertical shear in the ocean?

While there are areas with really strong tidal currents in the ocean, these currents tend to be primarily barotropic. My question relates to the largest vertical difference in velocity and it is ...
arkaia's user avatar
  • 15.4k
11 votes
1 answer
812 views

What tidal databases are available to be used as model boundary conditions?

I am trying to set up a coastal ocean model simulation. I am looking for different ways to force the tidal boundary condition in the model to study how uncertainty in the tidal forcing in the boundary ...
arkaia's user avatar
  • 15.4k
10 votes
1 answer
12k views

What visual wave behaviour help to tell if a tide is going in or out?

I have always wondered how someone could tell, by a brief observation (a few minutes at most), whether a tide is receding or advancing on a rainy day. Assuming there is no access to tide times and ...
user avatar
10 votes
2 answers
525 views

Is the Earth heated up by the tides?

Reading about moons of other planets they often get heated up by the tides so for example Io and Europe of Jupiter get friction by which eruptions and liquid water can arise. But is there also an ...
Marijn 's user avatar
  • 2,523
9 votes
3 answers
911 views

How is sea level measured?

In comments on Earth changes due to global climate change, sea level changes is a common topic. I hear quotes about sea level changes in the centimeter and even millimeter range and wonder how such ...
user avatar
9 votes
2 answers
291 views

How was Venice flooded?

If I understand this correctly, Venice was not flooded due to sudden rainfall causing rivers to overflow, but due to the high tides. These high tides were caused by an alignment of sun, which was ...
Martin Drozdik's user avatar
9 votes
1 answer
1k views

The motion of tides

I found this animation from a satellite: which shows the motion and elevation of tides on a certain date. Can you find an animation of a date when there is a spring tide? my question is as follows: ...
user avatar
8 votes
2 answers
128 views

What goes into a tide power prediction for every fifteen minutes over the next twenty five years?

I was watching a segment about tidal power generation on a PBS NewsHour broadcast. I've set the time code at about 11:45 to capture a little background. This bit ...
uhoh's user avatar
  • 7,096
8 votes
1 answer
752 views

How come the tide is low when the moon is high in the sky

Happily spending my holidays in the Fiji Islands, I noticed a couple of days ago that when the moon was very high in the sky (my shadow was maybe 0.5-1m long) the tide was low. That really puzzled me....
Nodjo's user avatar
  • 83
8 votes
1 answer
1k views

How to Calculate the Equilibrum Function for use in Tide Calculations using Harmonic Constituents

I have found a wealth of information using Harmonic Constituents to calculate tide levels. H(t) = Amplitude * cos ( t * harmonicSpeed + phase lag). Yet when I try to apply this to constituents from ...
user avatar
7 votes
1 answer
151 views

Tidal flow in an estuary

I am working on a project. Where this bacteria has been deposited at a port in the Humber Estuary. Where it has been deposited has been marked in red. I am trying to work out the limits of where this ...
00100's user avatar
  • 73
6 votes
2 answers
4k views

Why do high tides vary month to month?

I've noticed that some ‘highest‘ high tides in one month are bigger than the highest high-tide of previous months. Why is this so?
lithium123's user avatar
6 votes
3 answers
500 views

Do flights affect tides?

Can artificial satellite positions affect tides? on Space Exploration.SE asks if artificial satellites can affect tides, because they are a lot closer than our natural satellite, even though they are ...
WBT's user avatar
  • 300
6 votes
2 answers
557 views

Why is the time interval between tides so irregular?

Looking at the tidal calendar for the German North Sea, I wonder why the interval between times is so irregular. Internet searches lead to pages that say the tides should be regular 24 hours 50 ...
user27467's user avatar
6 votes
1 answer
245 views

Calculating Love numbers (tidal deformation) for non-homogeneous planets

I have a question about planetology. I'm not sure if it belongs here, but the astronomy stack exchange seemed a bit odd, too. I would like to enhance my understanding of Love numbers. Love numbers ...
theWrongAlice's user avatar
5 votes
3 answers
525 views

Is it possible to predict the maximum daily/annual tide height without calculating hourly heights?

It's possible to predict tide at a given location and at a given time reasonably well (e.g. predicting low tide). And there are tools available that make it possible to do this calculation for any ...
naught101's user avatar
  • 5,415
5 votes
1 answer
1k views

Definitions of tidal harmonic constituents...?

Does anyone know where there is a detailed definition for tidal harmonic constituents? There is loads of stuff on $M_2$, $S_2$, $N_2$, etc. (all the common ones), but there are a great many more, some ...
bobg1756's user avatar
  • 123
5 votes
1 answer
704 views

What are the effects of underwater "windmills"?

Most early examples of tidal energy generators used barrages (damns) to generate electricity (La Rance, Kislaya Guba, Annapolis Royal). Meanwhile, a lot of newer projects use rotary blades in the ...
arkaia's user avatar
  • 15.4k
5 votes
1 answer
106 views

What proportion of the energy input to the ocean tide system comes from the sun?

The earth's ocean tides are primarily driven by the moon, but also by the sun. The relative strengths of the related tidal constituents varies from place to place across the globe. But what is the ...
Semidiurnal Simon's user avatar
5 votes
2 answers
89 views

Difference between two types of spring tides that occur every month

A spring tide is an unusually high tide that ooccurs when the sun, earth, and moon are colinear. I understand why this would be the case when the earth is on the far side of the sun and moon. The ...
aquagremlin's user avatar
5 votes
0 answers
38 views

Is it possible to know the tides of a particular location 50 years or 100 years from now?

Assuming no change in sea level (for the sake of argument), is it possible to know the high and low tides a half century or more in the future? Is information like this available to the general ...
Bob516's user avatar
  • 334
5 votes
1 answer
221 views

Why is the tidal range at the entrance to the bay of fundy so high?

This question is a continuation of my previous question: Questions about the validity of a certain model for tidal resonance at the Bay of Fundy. I need to answer this question in order to return to ...
user2554's user avatar
  • 191
5 votes
1 answer
174 views

If the distance between Earth and the moon were changed, would the effects be immediate? [closed]

I need your help on a possible (but perhaps low probability) scenario for how the distance between Earth and the moon could change: say a large object from the Kuiper Belt manages to make its way into ...
Leigh P.'s user avatar
4 votes
2 answers
565 views

What was the storm surge height from Hurricane Harvey?

The numbers bandied about have been 3.6 m (12 feet) and even 4.6 m (15 feet), but something told me that was unlikely. As a guy who could "almost" slam dunk a basketball, the idea of a 3 m (10 feet) ...
Oliver Williams's user avatar
4 votes
1 answer
166 views

Relationship between tides and earthquakes

Ide et al. (2016) suggest that earthquakes (especially those of high magnitudes) are more probable during periods of high tidal stress (during full and new moons). While they show a comprehensive ...
arkaia's user avatar
  • 15.4k
4 votes
2 answers
2k views

When specifying phase and amplitude for a tidal constituent, what date/time does phase start from?

It is common to describe tidal elevations at a given location by giving the phases and amplitudes of tidal constituents. One such application is for setting the open boundary conditions for regional ...
Semidiurnal Simon's user avatar
4 votes
1 answer
244 views

Effects of Dredging Estuary Channel on Water Flow

Is it possible to make some generalizations about the hydrographic effects of dredging a channel into an estuary? Or is it too complex a problem and each case must be considered independently? Let me ...
tkreyche's user avatar
4 votes
1 answer
69 views

Why do ocean tides have negative and positive terms in their effects on Stoke's coefficients for calculating geopotential?

I have recently started working on calculating a Geopotential model based on GGM05C. In order to obtain a model as accurate as possible, some corrections must be applied to the normalized Stokes' ...
Rafa's user avatar
  • 233
4 votes
1 answer
2k views

How often do king tides (perigean spring tides) occur?

Recently, there has been a lot of information about "King Tides" (i.e, perigean spring tides) on the news with a number of groups relating the peak king tide to future normal conditions (2050) under ...
arkaia's user avatar
  • 15.4k
4 votes
1 answer
95 views

High tides at Venice

I read somewhere that the new MOSE system can withstand a maximum rise in water of about 3m. I was wondering if that extreme case will happen on the coast line of Lido di Venezia, there will be a ...
yngabl's user avatar
  • 161
4 votes
0 answers
56 views

Simple numerical model of tide with an elliptic scheme

I have recently been given the task of developping a coastal model for tides. I have a few requirements, it must not be time stepping in order to be as fast as possible and in finite differences ...
Koekoe94's user avatar
4 votes
0 answers
131 views

Presence of cross stratified conglomerates in fan deltas

Why are cross stratified conglomerates found in deposits of fan deltas? I know that fan deltas are alluvial fans that deposit directly into the sea, hence they are poorly sorted.But could not ...
Faraz Gerrard Jamal's user avatar
3 votes
2 answers
2k views

What would be the impact on tides if the earth had no tilt?

I would like to know what would be the impacts/effects on the tides if earth were to have no tilt (perpendicular to plane of ecliptic)?
Kait's user avatar
  • 111
3 votes
1 answer
199 views

What would be the effect of a geostationary moon?

What kinds of differences from our Earth would we see with a moon in a geostationary orbit over the equator? Assuming the gravitational pull is roughly the same as it is with ours (my back of the ...
Sarah's user avatar
  • 133
3 votes
1 answer
642 views

"Major Lunar Standstill" causing high tides?

The Major Lunar Standstill, as the cycle is called, has been followed by serious starwatchers since the Babylonians. Like clockwork every 18.6 years, it triggers severe tide spikes, swells, and floods,...
Keith McClary's user avatar
3 votes
1 answer
2k views

Why don't spring tides occur at full/new moon (age of tide)?

Tides observations everywhere show that spring tides occur not at full or new moon, at the time of maximum driving forces, but typically a day or two later. What causes this delay?
arkaia's user avatar
  • 15.4k
3 votes
1 answer
65 views

Do the 600 satellites that orbit the Earth have any gravitational pull on the tides like the moon?

I know that space is big and satellites are small compared with the moon, but do they have, or will they if we get more, any effect on the sea and ocean water on the earth?
rhett's user avatar
  • 121
3 votes
1 answer
132 views

Global tide calculation

I am familiar with the concept of harmonic tide coefficients and was wondering about the simplest software solution to calculate tides anywhere, worldwide. Are there any available, open source ...
El Dude's user avatar
  • 161
3 votes
2 answers
351 views

How large were Mars' ocean tides and to what extent could they keep the oceans mixing and tend to keep salinity uniform? Has this been modeled?

This answer to Salinity of Martian water 3.5 Billion years ago in Astronomy says that most estimates of Mars' ocean's salinity are pretty high; The article "Water Activity and the Challenge for ...
uhoh's user avatar
  • 7,096
3 votes
1 answer
2k views

How much do tides affect earth's rotational velocity?

Many of us are familiar with an exaggerated picture of the Moon's effect on Earth's tides: Since the Earth is not uniformly covered with water, however, I imagine that the tidal effect will depend on ...
Ben Sandeen's user avatar
3 votes
0 answers
21 views

How to de-tide a daily averaged sea level data?

Coud you help me to resolve this situation? : I have a raw daily averaged sea level time series, as you know when we perform a harmonic analysis (e.g. using T_Tide from MATLAB) we need to put our data ...
Miguel 's user avatar
  • 353
3 votes
2 answers
118 views

Do tidal forces affect subduction?

I know subduction in plate tectonics is mainly density driven. Probably a hypothetical question, but can weaknesses caused by tidal forces have an influence on the start of a subduction zone? Would ...
user avatar
3 votes
0 answers
116 views

How do I determine the phase lag for a tide

I want to determine the height of a sine wave for some tidal constituents for which I would use the following equation: 𝑌(𝑡)=𝐻cos⁡(𝜔𝑡−𝜙), where H is the amplitude, 𝜔 is the speed of rotation, t ...
Claire's user avatar
  • 31
3 votes
0 answers
115 views

Questions about the validity of a certain model for tidal resonance at the Bay of Fundy

I'm currently working on a (relatively-simple) fluid-dynamics model of the tidal resonance at the Bay of Fundy, a place which is known for his world-breaking tidal range (15 meters on average, while ...
user2554's user avatar
  • 191
2 votes
2 answers
241 views

What has been the influence of the moon on Earth's temperature?

What proportion of Earth's internal heat is generated by tidal flexion as a result of the orbiting moon, and would it have been significantly greater four billion years ago when the moon was closer? ...
Michael Walsby's user avatar