Pedant's definition of a spring tide?

[dedwards]

Hi All,

I have been thinking: in the strictest sense of the term, when is a spring tide officially a spring tide?

i.e. Is there always only one spring tide per cycle or can you have multiple spring tides during a particularly springy spring? Also, is it possible to not have a spring tide at all during a particularly neapy spring?

Hope this doesnt sound like i'm trying to start an anchor-style argument: I am genuinely interested to know the answer.

 

[Evadne]

I think you can get a bit too tied up in the definition, which is a man-made simplification of a natural phenomenon. I don't think you can say one day's tide is The Spring Tide for that month, because in the tide you are really referring to the observed hydrographical effect rather than the underlying astronomical cause.
As you know, "Springs" is when the sun and moon conspire to make the tidal range greater, "neaps" is when they oppose to make it lesser. At some ports this results in one biggest tide followed and preceded by lesser tides, at others, or at the same port in other months you can get two or more tides of equal range. The highest high, lowest low and greatest range do not necessarily occur on the same tide.

 

[dylanwinter]

marsh tides

I think you can get a bit too tied up in the definition, which is a man-made simplification of a natural phenomenon. I don't think you can say one day's tide is The Spring Tide for that month, because in the tide you are really referring to the observed hydrographical effect rather than the underlying astronomical cause.
As you know, "Springs" is when the sun and moon conspire to make the tidal range greater, "neaps" is when they oppose to make it lesser. At some ports this results in one biggest tide followed and preceded by lesser tides, at others, or at the same port in other months you can get two or more tides of equal range. The highest high, lowest low and greatest range do not necessarily occur on the same tide.

Never heard anyone use the term spring tide while I have been in Wells

the high tides are referred to as "marsh tides"

which means that they cover the marsh

anyway,

this theory about the atoms of the sea water talking to the molecules and atoms on the moon (too far away to shout at) and the sun (even further away)

oh come on ....

that can't be true

tell me how it works and I will beleive you

meantime ....

us realists know that the tides are caused by Neptune breathing

Dylan

 

[sarabande]

don't forget Proxigean spring tides...

The Extreme Proxigean spring tides occur in theory every 31 years.


(pednat, ex Geography teacher )

 

[Simes]

Hmm,

In an attempt to answer to OP question.

At any one Standard Tidal Port you will find the "Mean Range" of tide at both Springs and at Neaps, This information is provided in Reeds in a small box on the Tidal Curve for each port.
In general terms it is accepted that you are at Springs if the Range of tide for the period that you are interested in is within 0.5 of a metre of the Mean Spring range. This is not a hard and fast rule, just guidance.

For instance at Portsmouth the Mean Spring range is 3.9m and the range this lunch time is 3.7m. So you are probably going to use the Spring curve of the Tidal Graph.

You may find it easier to refer to "Big Springs" or "Small Springs" according to the size of the range.

Hope that this helps,

Simes (PM me for more info)

 

[Skylark]

I'm happy to be corrected but my understanding is that, strictly speaking, it is a spring only on the tide whose height is that of the published spring height for the standard port in question.

Sounds pedantic but from memory that's what I was told.

 

[PoRL9]

I'm happy to be corrected but my understanding is that, strictly speaking, it is a spring only on the tide whose height is that of the published spring height for the standard port in question.

Sounds pedantic but from memory that's what I was told.

Thing is - as has been said previously - there is no specific spring height for a port as it's different on every lunar cycle, and an average value from all possible cycles (The "mean high water springs") is given instead.

The only other value given is the highest astronomical tide (which is only really useful for clearances under bridges, etc).

 

[emsworthy]

don't forget Proxigean spring tides...

The Extreme Proxigean spring tides occur in theory every 31 years.


(pednat, ex Geography teacher )

Think we may have guessed not "ex-English teacher"!

 

[Twister_Ken]

don't forget Proxigean spring tides...

The Extreme Proxigean spring tides occur in theory every 31 years.


(pednat, ex Geography teacher )

Typical bloody pednat!

 

[Seajet]

Back on Planet Earth, 'Spring Tides' happen every 2 weeks, alternating with 'Neaps'.

Springs go up higher & down lower than Neaps, so consequently flow faster to deal with the volume of water; on my half tide mooring there's actually more water around at half tide during Neaps.

A look at the highs and lows on a local tide table is a clue, these are available on the internet but do double check, bogus figures are not unknown !

 

[guernseyman]

A spring tide is caused when the earth, moon and sun are aligned (syzygy) and occurs a couple of days later. Thus they occur roughly at fortnightly intervals after full and new moons.

The heights of spring tides vary considerably (by 25% round here) between the solstices and the equinoxes.

 

[Sybarite]

Hi All,

I have been thinking: in the strictest sense of the term, when is a spring tide officially a spring tide?

i.e. Is there always only one spring tide per cycle or can you have multiple spring tides during a particularly springy spring? Also, is it possible to not have a spring tide at all during a particularly neapy spring?

Hope this doesnt sound like i'm trying to start an anchor-style argument: I am genuinely interested to know the answer.

Think of oscillating curves where some are higher than others.

 

[LittleSister]

Think of oscillating curves....

Oooh. You are awful!

 

[dedwards]

Thanks to all the responses so far. especially simes who has so far provided the closest answer to what I was looking for.

to those who described when and why springs happen, I fully understand all that. what I was getting at is, for example, on a big spring, is the day before it also 'a spring tide'? If so, what about the day before that? and so on... and therefore at what point do they stop being springs and become 'normal'?

Alternatively, is the definition of a spring tide the single tide that is the highest tide when the moon etc are in line regardless of its height? This would mean that a 'spring' in one cycle can actually be lower than a non-spring in another cycle.

I fully recognise the early response about the exact definition not being that important, but I find it an interesting question non the less and it is probably telling that I have never seen any tidal publication that marks a tide as 'Springs'.

So, does anybody have any opinion that differs from simes's "any tide within 0.5m of MHWS"?

 

[guernseyman]

Thanks to all the responses so far. especially simes who has so far provided the closest answer to what I was looking for.

to those who described when and why springs happen, I fully understand all that. what I was getting at is, for example, on a big spring, is the day before it also 'a spring tide'? If so, what about the day before that? and so on... and therefore at what point do they stop being springs and become 'normal'?

Alternatively, is the definition of a spring tide the single tide that is the highest tide when the moon etc are in line regardless of its height? This would mean that a 'spring' in one cycle can actually be lower than a non-spring in another cycle.

I fully recognise the early response about the exact definition not being that important, but I find it an interesting question non the less and it is probably telling that I have never seen any tidal publication that marks a tide as 'Springs'.

So, does anybody have any opinion that differs from simes's "any tide within 0.5m of MHWS"?

Reeds Nautical Almanac marks each (single) spring and neap tide.

More broadly, tides in the spring cycle are described as 'springing', and those in the neap cycle as 'neaping'.

Clearly sime's definition is wrong, although it might apply in a location with small tides.

 

[DanTribe]

I believe the antipodeans call them king tides.
So do I sometimes when trying to row against them.
" Will you look at this 'king tide!"

 

[johnalison]

Our son is still smarting from an occasion 30 years ago when he was asked in a quiz

"What are the highest tides called?"

A "Spring tides"

"Correct. What are the lowest tides called?"

A "Spring tides"

"Wrong"

 

[alahol2]

We usually use terms like...
Coming up to springs, falling off springs, a high spring, a low spring, etc etc.
So a spring tide happens every fortnight whether it be a high spring or a low spring and, yes a low spring may well be lower than a tide that is just 'coming up to springs' on a high spring cycle.

 

[BobGee]

In my humble opinion (I understand that translates to IMHO in webism).....

The terms 'spring' and 'neap' merely refer to the upper and lower limits of a predictable, continual and variable tidal cycle (view any tide graph for a whole month/year and you will see what I mean)

The answer to your question is that spring and neap tides are a process, a rhythm, and not an event.

There is always room for interpolation as to what are 'springs' and what are 'neaps'. Therefore, (an additional answer to your question) the days before a spring are interpolated accordingly (but don't have a name other than perhaps..."coming up to springs". Likewise, the day before a full neap, or after, or two days before etc etc, don't have a name other than that derived by you such as : 'almost neaps'...just coming up to neaps...etc etc.

I feel this is about semantics rather than accuracy of tidal prediction, therefore whatever name you choose to accord to those variations are entirely up to you.

They are all 'normal' tides, springs are the ones with the largest volume and neaps the ones with the smallest volume. Whatever you call the progressive variations in between is entirely a matter for your good self and the pedagogues that give a hoot.

Peace and love

BobGee

 

[alan_d]

The answer to the OP's question, as to so many others, is "It all depends..."

There is no exclusive "official" definition, so in this case it depends on what you want to use the term "spring tide" for.

If you want to designate the tide with the greatest range in the two-week cycle, then it only applies to one tide on one particular day. If you want to know whether to use the Springs or Neaps line on a tidal curve then you will make a judgement based on how the range for the day compares with the mean spring range. If you just want to indicate whether the range for the day is large or small you might call it springs if the range is closer to the mean spring range than the mean neap range. It is commonplace to refer to "big spring tides" when the range is significantly greater than the mean spring range.

For all tidal calculations, what matters is the range for that particular tide; it makes no difference, for example, whether that range occurs at the maximum for that cycle or at some other point.