The Moon and Spanish plumes

[Summer of 95]

Today a Spanish plume finally came off up here, with the temperature currently 32C. This is the first time we've hit 30 since 2006.

Last night I was outside and I noticed a full moon shining brightly. So I just looked up the dates of previous successful plumes (I count them successful if the temp here reaches 30C, or it reaches 28C with plenty of sunshine and a good T-storm) and the moon phase. I couldn't believe the results:

3-4 Aug 1990: Moon 91-94%, waxing, full moon 6 Aug. (Warmest ever)

10-11 July 1995:  95-99%, waxing, full 12 July (30C followed by memorable all-night storm)

3-4 July 2001: 96-99%, waxing, full 5 July (classic 3 days and a thunderstorm, hit 30C)

9 Aug 2003, 92%, waxing, full 11 Aug (maybe not a classic plume, but similar enough, 33C)

19-20 June 2005: 91-96%, waxing, full 22 June (brilliant thunderstorm with large hail, after touching 30C- last successful plume before today)

18-19 July 2016, 100%, full on 19 July. 32C/90F reached

And the flops, either not warm enough, too cloudy, no heat outside the SE....

27-28 May 2005, 83-73%, waning, full 23 May (was sunny but the heat confined itself to SE, near miss)

30 June-1 July 2009: 61-73%, waxing, full 7 July (just cloudy and humid, real heat only in E/SE)

18-19 Aug 2012: 1-5%, waxing, full moons 2 and 31 Aug (the biggest flop of all, cloudy, damp and barely above 20C when it hit 30 in London)

1 Aug 2013: 25%, waning, full 20 Aug (12-hour wonder, arrived too late to clear the cloud and didn't last to give the following day a go)

30 June-1 July 2015: 97-100%, waxing, full 2 July (only just a failure, it reached 30C and thundered only 30 miles away). It failed because of stubborn cloud that sat over us all day while nearby was clear, nationally probably a success.

All the successes occurred near full moon, with 90% phase or more. The failures (except for 2015 which was a marginal and very local failure) were all away from full moon, notably the biggest flop of all in 2012 was near new moon. So why do they only affect areas outside the SE when the moon is close to full? Gravitational effects perhaps?

[Roger J Smith]

June and early July full moons will occur at the southern declination maximum (notice how low the full moon is in the sky tonight).

May full moons will occur 3-4 days before that, August 3-4 days after. 

So perhaps the real driver is the declination cycle and not the phase. That's what my research tends to show. There are winter storminess peaks at northern and southern max more so than full and new moon although there again, the phase and declination peaks overlap in December and early January (the opposite of summer, full moon is at northern declination max then). 

I don't think your list is a coincidence either. But obviously each opportunity is not realized, it's just one piece of the puzzle. 

[Summer of 95]

39 minutes ago, Roger J Smith said:

June and early July full moons will occur at the southern declination maximum (notice how low the full moon is in the sky tonight).

May full moons will occur 3-4 days before that, August 3-4 days after. 

So perhaps the real driver is the declination cycle and not the phase. That's what my research tends to show. There are winter storminess peaks at northern and southern max more so than full and new moon although there again, the phase and declination peaks overlap in December and early January (the opposite of summer, full moon is at northern declination max then). 

I don't think your list is a coincidence either. But obviously each opportunity is not realized, it's just one piece of the puzzle. 

Interesting about the stickiness and declination peaks, is that just for the UK or elsewhere as well? Is it affected by some moons being north of the ecliptic and some south as well? I'll have to check the declination of the plume moons now...

[Evening thunder]

What about the 19th July 2006 which reached 33C at Shawbury (unless you don't count that as a plume)

Waning -  32%

[East_England_Stormchaser91]

Late July or August 2004 im sure had near enough a full moon too. I seem to remember the lightning flashes directly infront/below the moon off to the East/Southeast. Quite a stunning sight to see! 

[Roger J Smith]

I should caution that an extensive number crunch of all CET data shows only faint signals related to lunar declination or phase. Over about 245 years of daily data now the phase signals are seldom larger than 0.1 C deg and declination sometimes reaches 0.3 C deg, about 10% of the general variance of data. But I checked my data and found that the peaks are more aligned to southern maximum than full moon as you get away from mid-summer solstice when they are currently aligned (this shifts over very long cycles but has only moved about 3 or 4 days over the span of this data). 

I also did a frequency check for record daily temperatures and found it generally randomly distributed but with small peaks around the declination peaks. So I came to the conclusion that perhaps there is a weak lunar tide in the atmosphere at key longitudes (the same effects are shown in eastern North American data) but it would stand to reason that there would have to be some sort of large-scale interference pattern because not all longitudes would be expected to show peaks on the same dates relative to the forcing if there was a slow tidal influence rotating around the subtropical highs perhaps. 

My conclusion is that if the atmosphere is in fact being subjected to external forcings of this kind, other non-lunar effects must be larger players. But there would be room to investigate whether the declination cycle is enhanced at certain points in the 18.6 year cycle of declination, or relative to the 8.85 year cycle of lunar perigee at given declinations (perigee moves slowly forward against declination, at the present time it is about midway between southern and northern maximum and drifting towards northern maximum). If there were a weak signal you might expect it to be stronger if perigee occurred at the forcing point (just like moving a fan a bit closer to your sweating body which is what I just did). 

As northern maximum is just as strong a warming influence as southern, in June-July I might expect an equal number of heat waves near the new moon too. This is certainly the case in the North American data, and northern max is especially good for warm spells in autumn, when it comes a week before full moons. A fairly common regime in the data is for a long warm spell to crest at northern maximum then break down with the full moon, with colder than normal conditions peaking around seven to ten days after the full moon. This is a statistical profile more than a predictive tool if you see the distinction. Sort of like saying cold years are more likely at solar minimum. 

 

 

[iapennell]

There is an effect on the atmosphere caused by full moons (similar at new moons) in similar fashion to the manner in which the new and full moon causes tides. At these times the gravitational impacts of sun and moon combine to cause the atmosphere to pile up in locations facing the Sun and moon directly. The combined frictional impact due to the rotating Earth will be such as to slow the eastwards angular momentum of the atmosphere. As with marine tidal friction the effect is very small but it could account for some of the statistically significant weather associated with full and new moons.

If the global atmosphere loses Westerly momentum a little at full or new moon there is liable to be more of the weather associated with weaker westerlies reaching Britain: In summer that means more in the way of hot sunny weather can occur whilst in autumn and winter this increases the likelihood of settled weather bringing night frosts and fog. 

However the effect must be very small. It is estimated that the effect of marine and atmospheric tidal friction caused by the Sun and moon would take something like 1.5 billion years to slow the Earth's rotation by just half. It is therefore likely as not that full or new moons and atmospheric tides have no significant impact on the British weather at all!

Edited July 22, 2016 by iapennell

[iapennell]

Just to add there is historical weather lore related to full moons, viz :

1) The Full Moon eats clouds. 

2) Full Moon. Tonight will be frosty!

In winter, a full moon at perigree will not only be high in the sky in the Northern Hemisphere at nigh but being closer to Earth the tidal impact on the atmosphere (and particularly the strong upper Westerlies) would be greater as a result. Result: Less "need" for strong Westerlies to counter-balance tropical Easterlies to satisfy Conservation of Angular Momentum laws which means more high-pressure bringing clear cold winter nights over Britain when such winter full moons occur. 

Perhaps there is a grain of truth in rather more of these old weather sayings than we like to give them credit! 

[PersianPaladin]

On 7/22/2016 at 23:18, iapennell said:

There is an effect on the atmosphere caused by full moons (similar at new moons) in similar fashion to the manner in which the new and full moon causes tides. At these times the gravitational impacts of sun and moon combine to cause the atmosphere to pile up in locations facing the Sun and moon directly. The combined frictional impact due to the rotating Earth will be such as to slow the eastwards angular momentum of the atmosphere. As with marine tidal friction the effect is very small but it could account for some of the statistically significant weather associated with full and new moons.

If the global atmosphere loses Westerly momentum a little at full or new moon there is liable to be more of the weather associated with weaker westerlies reaching Britain: In summer that means more in the way of hot sunny weather can occur whilst in autumn and winter this increases the likelihood of settled weather bringing night frosts and fog. 

However the effect must be very small. It is estimated that the effect of marine and atmospheric tidal friction caused by the Sun and moon would take something like 1.5 billion years to slow the Earth's rotation by just half. It is therefore likely as not that full or new moons and atmospheric tides have no significant impact on the British weather at all!

That's very interesting. Is there any scientific literature or meteorological sources that might expand on this?

[Methuselah]

7 minutes ago, PersianPaladin said:

That's very interesting. Is there any scientific literature or meteorological sources that might expand on this?

I suspect that there isn't, PP...It could be similar to all those claims about more murders, rapes and burglaries occurring at the full moon: in the days when those associations were first mooted, there were neither streetlamps nor flashlights - go figure?

[Relativistic]

Another plume being modelled for Monday to Wednesday next week. On Wednesday we have a 99% full Moon. Assuming it occurs as forecast, that'll be another one to add to the list.

[Nouska]

1 hour ago, Relativistic said:

Another plume being modelled for Monday to Wednesday next week. On Wednesday we have a 99% full Moon. Assuming it occurs as forecast, that'll be another one to add to the list.

Interesting topic and something I noticed last year with the very hot summer in Europe. I remember speculating on the timing of the next plume, based on the observed periodicities in the preceding months.

Being as it was rare for the heat to get into Britain last summer, I attach the temperature graph for my location. You can see the regular spikes from March onwards but why were they so regular? Fewer days than a moon cycle and not precisely coinciding with full moon.

@Roger J Smith you have done a lot of work on this subject, any thoughts?

 

[Roger J Smith]

Scroll back a few posts, I already posted something about this. There is a weak correlation but I don't claim that the lunar effects are strong enough to be cause and effect explanations of such phenomena. If you take any given year the lunar signal always looks larger than the long-term signal, this suggests to me that some other factors with reasonably similar periods are at play and overlapping the weaker lunar signals. 

[Roger J Smith]

I had a close look at my data for the lunar signals and all that shows up is a very faint temperature peak before the July full moon in either all data (1772 to 2011) or the 25 warmest summers in that period. 

For all data, there is a peak of +0.16 deg (C) for the date four days before the July southern declination maximum which is typically 1-3 days before a full moon. This peak seems to last about 4-5 days at similar intensity then fades out. For comparison, the coldest day in the next 30 days (relative to the 1772-2011 average) is -0.17 deg which occurs eight days after the southern max or about five to six days after full moon. 

Then there is another peak of +0.20 deg at about the late July or early August northern maximum about 3-5 days before a new moon at that point in the data. This is followed by a relative minimum of -0.24 deg (C) about four days before the southern maximum of August data, and that is followed by a peak at +0.19 deg (C) at a date corresponding to about 2-3 days after full moon in August..

Now for the warmest 25 years where the baseline is about 1.5  deg above normal, the peaks are shown at +1.7 deg just after the July full moon and +2.1 deg around the August full moon, however, the warmest signal in these hot summers comes around the week that begins with a northern declination maximum and new moon in the period 16 June to 15 July. Here the peak reaches +2.6 deg on average for about a week. 

I found similar peaks in the Toronto data. My working hypothesis is that the Pacific and Atlantic Oceans may spin off somewhat larger amounts of warmth after the northern maximum, in other words, the jet stream is likely to be pushed a bit north and perhaps will contain more well-defined warm sectors. The differences are rather subtle and so I don't draw any conclusions that the Moon is driving the weather machine, more like that it has a bit of an influence along with a large number of other factors. 

But the data do support the notion that there is a slightly elevated chance of a warm spell at or near full moon in mid-summer.

 

.

[Nouska]

13 hours ago, Roger J Smith said:

Scroll back a few posts, I already posted something about this. There is a weak correlation but I don't claim that the lunar effects are strong enough to be cause and effect explanations of such phenomena. If you take any given year the lunar signal always looks larger than the long-term signal, this suggests to me that some other factors with reasonably similar periods are at play and overlapping the weaker lunar signals. 

Thanks for the very detailed responses - just another of the tiny cogs in the big wheel of atmosphere circulation.

[Relativistic]

On 09/08/2016 at 12:07, Nouska said:

Interesting topic and something I noticed last year with the very hot summer in Europe. I remember speculating on the timing of the next plume, based on the observed periodicities in the preceding months.

Being as it was rare for the heat to get into Britain last summer, I attach the temperature graph for my location. You can see the regular spikes from March onwards but why were they so regular? Fewer days than a moon cycle and not precisely coinciding with full moon.

@Roger J Smith you have done a lot of work on this subject, any thoughts?

 

 

This might be of interest. I've plotted the dates of full Moons and the CET daily data together, for 2016.

The first two full Moons of this year definitely coincided with temperature spikes. The fifth full Moon also saw a reasonable spike, and the plume in July coincided (perhaps the wrong word to use?) very nicely with the seventh full Moon of the year. The other full Moons occurred around slight spikes, but these are not as pronounced.

Edited September 14, 2016 by Relativistic