<p>Spring tides occur typically a day or two after full moon and new moon.  My simplistic understanding is that the delay is due to inertia and friction.  I have noticed from tide tables over several years that the spring tides after a full moon occur, on average, later than those after a new moon.  For example, in 2022 at Dover, the delay after a full moon was greater than 1 day on 8 out of the 12 occurrences, including twice when it was 3 days, but the delay after the preceding new moon was greater than 1 day on only 5 out of the 12 occurrences and was never as much as 3 days.  Why is that?</p>

CC BY-SA 4.0
2024-09-25T05:33:29.763Z
Can you link to evidence that the premise of the question actually holds? Did you consider full and new moon timing at minute accuracy?
planetmaker
CC BY-SA 4.0
2024-09-25T07:49:47.477Z
The precise time of moon phases is readily available, but I have not found data at minute accuracy for the time of spring tide (as distinct from the time of high/low water). Often, around spring/neap tides, the tidal range, and the heights of high/low water, remain constant over more than one tidal cycle, so it is not possible from normal tide tables to determine the exact time of spring tides. Do you know where to find that information? However, if my observation is due to lack of precision, other years' data would show the opposite effect, but I have found that they show the same.
Steve Lenartowicz
CC BY-SA 4.0
2024-09-25T11:20:01.807Z
I looked at e.g. http://www.exnatura.de:9099/calendar/month/68.ics?y=2023&m=9&f=Webseite and compared the timing of the low tide with the rise time of the moon, and did not see a systematic trend in a brief look at the data. Can you describe (in an edit to the question) a bit more your findings and what times and things you compare, possibly giving examples and directly citing your sources and linking them if possible? I recon this requires a very careful look at the type of data one draws conclusions from to not get any aliasing effects or biases for whatever reasons.
planetmaker
CC BY-SA 4.0
2024-09-25T11:51:22.953Z
For a very detailed analysis one probably also would want to consider the inclination of the Moon's plane against the ecliptic, or its position above or below Earth's equator, not just the longitudinal position.
planetmaker
CC BY-SA 4.0
2024-09-25T13:34:15.117Z
Thank you for your feedback.  You may be correct that my premise might be false because of the weakness of the data.  I will seek more precise data about the times of spring tides (assuming that this is different from the times of individual high/low tides, as two or more successive tides can be the same height).  Do you know a source of such data, or even what is a definition of the time of a spring tide?
Steve Lenartowicz
CC BY-SA 4.0
2024-09-25T18:36:21.147Z
I know that I get the tidal information for the German bight from the German office for seafaring and hydrography... but behind a paywall. What I linked was just a random, but credible-looking source for these kind of information for historic data - but with unknown accuracy. Other countries will have similar information services, possibly even publicly available. Look for something like "tide historic data" or similar - preferentially in the local language of the places you look for. The actual time of the tides *does* depend quite a bit on the actual geography.
planetmaker
CC BY-SA 4.0
2024-09-26T09:31:57.690Z
maybe interesting: https://physics.stackexchange.com/questions/121830/does-earth-really-have-two-high-tide-bulges-on-opposite-sides
planetmaker
CC BY-SA 4.0
2024-09-27T11:27:09.370Z
Related, if not a duplicate: [Why don't spring tides occur at full/new moon (age of tide)?](https://earthscience.stackexchange.com/questions/8956/why-dont-spring-tides-occur-at-full-new-moon-age-of-tide)
David Hammen
<tides>
Why is the lag of spring tides after a full moon greater than that after a new moon?
Steve Lenartowicz
# Why is the lag of spring tides after a full moon greater than that after a new moon?

(Asked by: username_0 on 2024-09-24)

Spring tides occur typically a day or two after full moon and new moon. My simplistic understanding is that the delay is due to inertia and friction. I have noticed from tide tables over several years that the spring tides after a full moon occur, on average, later than those after a new moon. For example, in 2022 at Dover, the delay after a full moon was greater than 1 day on 8 out of the 12 occurrences, including twice when it was 3 days, but the delay after the preceding new moon was greater than 1 day on only 5 out of the 12 occurrences and was never as much as 3 days. Why is that?

**Tags:** tides

> **Comments:**
> **username_1**: Can you link to evidence that the premise of the question actually holds? Did you consider full and new moon timing at minute accuracy?  
> **username_0**: The precise time of moon phases is readily available, but I have not found data at minute accuracy for the time of spring tide (as distinct from the time of high/low water). Often, around spring/neap tides, the tidal range, and the heights of high/low water, remain constant over more than one tidal cycle, so it is not possible from normal tide tables to determine the exact time of spring tides. Do you know where to find that information? However, if my observation is due to lack of precision, other years' data would show the opposite effect, but I have found that they show the same.  
> **username_1**: I looked at e.g. http://www.exnatura.de:9099/calendar/month/68.ics?y=2023&m=9&f=Webseite and compared the timing of the low tide with the rise time of the moon, and did not see a systematic trend in a brief look at the data. Can you describe (in an edit to the question) a bit more your findings and what times and things you compare, possibly giving examples and directly citing your sources and linking them if possible? I recon this requires a very careful look at the type of data one draws conclusions from to not get any aliasing effects or biases for whatever reasons.  
> **username_1**: For a very detailed analysis one probably also would want to consider the inclination of the Moon's plane against the ecliptic, or its position above or below Earth's equator, not just the longitudinal position.  
> **username_0**: Thank you for your feedback.  You may be correct that my premise might be false because of the weakness of the data.  I will seek more precise data about the times of spring tides (assuming that this is different from the times of individual high/low tides, as two or more successive tides can be the same height).  Do you know a source of such data, or even what is a definition of the time of a spring tide?  
> **username_1**: I know that I get the tidal information for the German bight from the German office for seafaring and hydrography... but behind a paywall. What I linked was just a random, but credible-looking source for these kind of information for historic data - but with unknown accuracy. Other countries will have similar information services, possibly even publicly available. Look for something like "tide historic data" or similar - preferentially in the local language of the places you look for. The actual time of the tides *does* depend quite a bit on the actual geography.  
> **username_1**: maybe interesting: https://physics.stackexchange.com/questions/121830/does-earth-really-have-two-high-tide-bulges-on-opposite-sides  
> **username_2**: Related, if not a duplicate: [Why don't spring tides occur at full/new moon (age of tide)?](https://earthscience.stackexchange.com/questions/8956/why-dont-spring-tides-occur-at-full-new-moon-age-of-tide)  

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## 0 answers

