Does it rain more at the weekend ?

Havn't read the articles, but I'm v suspicious ..there may be small localised effects. Usually related to my whereabouts on any particular golf course.

This could easilly be overcome if we hadn't standardised on the day/week relationship.

How come it's Monday all around the world when we havn't standardised other stuff?

Anyhow much of industry is on a 7 day schedule... so like I said..I'm sceptical (moi?)

Must go and be grumpy somewhere....(I'm still irritated by that stupid battery charger thread, what a contrast with the sensible switching regulator one...!)

Hey it's gotta be time for a tea break (well at least somewhere!)

Zebu later

Del

Why not sell the dry weekdays as timeshare?

It calls for a little global experiment. Decitime! Switch to a 10-day week, a 10-hour day, a 10 minute hour, a 10 second minute, and see what happens.... (PWSlack is not usually this provocative, or flippant!)

Damnation - now I'm going to have to search for that government proposal document I was given about 20 years ago on this very subject...I'm going out, I may be some time....

Well, knock me down with a feather...it appears that the metric measurement system came out of an aborted attempt by the French Revolutionists to introduce decimal time. You just can't trust a peasant who gets above his station (just like ol' OC over here). Wiki has an interesting article - google "decimal time" and there are plenty of others.

Surely, if the human race didn't want to take up decimal, it's because, deep down in our psyches, we know that base 10 is not the base on which the universe operates! Bases 2,3 4 and 12 are far more useful...and if we'd just started out by writing in base 12 (where 10₁₂ = 12₁₀), we would still have all the advantages of "decimal" maths. I wonder if the various constants would come out to be more "sensible" numbers. Is there a number base where pi is a rational number? (I could probably answer this if I bothered to think, and it's probably no...somebody stop me, I'm rambling...nurse!!!)

The "Govt White Paper" to which I referred earlier is hardcopy, carefullt filed in the depth (height?) of my attic. It will be weeks...

Base 4 is fine by me ... my 'thumb' is stuck half way up the back of my wrist !

(My claws are making one hell of a mess of this keyboard! )

I have to admit, eight was always my favourite - probably to do with octopus used to explain in in my maths book (well I was only 10!). I thnik 12 would be most useful though.

What year is it?

What year is it?

Gotta be a trick question as my mates Gregory and Julian can't seem to agree !

W're in the year 35, but new year is comming close.

I believe that in a base pi numbering system, pi would be rational. It's just that practically everything else would be about as irrational as me.

Sincerely

Bill

With this you are called the project leader.

When can we expect the detail plan?

Perhaps you can also investigate wether driving left or right has an influence too.

Here's an abstract from another article;

Cerveny and Balling examined and compared three different data sets
-- daily carbon monoxide and ozone measurements from a Canadian
monitoring station on Sable Island off the coast of Nova Scotia,
daily satellite-derived rainfall data for the Atlantic Ocean, and
databases of coastal Atlantic hurricane measurements. In each
case, when the two ASU scientists examined the data by day of the
week, they found significant differences between days, and similar
patterns of variation, with pronounced differences between
beginnings and the ends of weeks. All three sets of climate data
revealed a seven-day cycle.

"The human week is not a natural time period," said Balling.
"Human effect on weather is the only explanation."

"If you're going to go out boating in the Atlantic, you're going
to get wet if it's a weekend," Cerveny said. "And what we suggest
is that this is probably linked to the pollution cycle."

In examining precipitation in the Atlantic, they found no daily
variation when looking at the ocean as a whole, but a pronounced
sine-wave pattern of variation for just the coastal areas, with
average daily precipitation rising on Thursday and into the weekend
and then dipping from Sunday through the middle of the week.
Balling notes that when the team analyzed satellite data grid cells
for an area a little further away from the coast, they found the
same pattern, time-shifted in accordance with the rate of pollution
drift.

Though the study does not directly address causation, a comparable
fluctuation in the levels of East Coast air pollution points to an
obvious connection. The fact that coastal hurricane intensity data
taken from 1945 to 1996 follow a similar pattern (rather than being
statistically uniform for each day of the week, as one would
expect), supports this hypothesis.

I still haven't found a good data set to support the weekly cycle or rainfall.Most of the articles I've seen relate to the East Coast (USA) or Australia. I think poor old Blighty is too variable in it's weather to spot any such pattern (honest, I'm not being sneaky !).

The notion of a 7 day week seems to originate with solar observation etc. It's a little 'coincidental' that the supposed cycle of pollutants/rain also follows this, or is it ? The suggestion is that over 5 working days we kick up enough aerosol pollution to seed more rain, and when the pollutants get washed down at the weekend we can start over on Monday. If it's all true, then what would happen if we changed our working week - it's got to rain some time !

Post 9/11 I saw an article saying that there was a measurable temperature difference in the USA that corresponded to a reduction in air-traffic. Sorry, but I forget where. I think I need some more fact on all this, but it does have a plausible basis (yes, OK all, so do most hoaxes etc). Call me squeaking mad, but I think there may be some connection between pollution build up and weekly rainfall cycles - It's just a bit too small to notice.

<squeak>

A family member claimed once, incorrectly as it happens, to be having no effect on the World.

If one has no effect on the World, then one does not exist on the World. So everyone has some effect.

Now multiply that by >6*10⁹....

Don't forget all those butterflies flapping their wings...they cause bloody chaos!

Never mind al the scientific stuff! Of course it rains more the weekends! Thats what the weekends are for! Bank holidays doubly so!

(Anyone outside of the UK need not respond)

Weekends? In July it rained every bloody day. Spencer.

Defra official trying out new weekend recreation wear.

I believe there could be a natural cycle of weather patterns which is almost, but not quite, 7 days. This means that several weekends in a row may be wet, but as the pattern shifts there can equally be several consecutive sunny weekends. I'm in southern England, and most of our rain recently has been during the week, with some very pleasant weekends in between.

Look at a weather satellite photograph of the globe and there are clearly repeating patterns of cloud which drift from west to east. This must result in some cyclical pattern to local weather. Maybe the whole concept of the 7 day week began on this basis.

It seems to me that a lot of people these days are far too ready to attribute every weather phenomenon on man-made causes.

I'm just stirring the pot, to see if anybody knows of something to support/reject the notion of human activity leading a 7-day weather cycle. Here's a further link.

Looking at records from 100s of years back may be futile because of inaccuracy or records and climate change cycles. Since this topic relates to weather change, maybe there is some chance of deciding upon it. Where countries have a widely used holiday week, some effect might be expected (?). Having been unable to find data on this, I was hoping somebody might know of such.

A propos of human activity and rainy sundays. A long time ago proponents of thought transfer, direct influence of wish etc etc. etc. proposed the following data collection process:

The hypothesis was that lots of people, tens of millions, were costantly wishing for non-rainy sundays. If their collective wish has any effect, statistics would show a relatively low incidence of rainy sundays.

Well, it seems that there is an opposite effect...

Presumably then this also proves that Big G either doesn't exist or has odd sense of humour?

Ahhh, Kris, you did not fall for that, did you? The weather knows only the season, not the day of the week. However, a standing riddle in Houston, Texas is; "What follows two days of rain in Houston?". The answer is, of course; "Monday!".

I do believe most of us, especially the young, notice inclement weather on the weekends since it does interfere with our beach parities and parking on the hilltop with the convertible top down.

How much annual rainfall does Houstan get, anyway?

It's more an idle curiosity thing really. A recent light-hearted trivia show (BBC 'QI') mentioned this, and I suddenly thought 'hmmmm'. Weather is something of a national obsession over here. Looking into this particular issue was a way of looking at effect of pollutants on rainfall without getting into _{global warming (shhh).} No doubt about rainfall changing with Season, but I don't think that changes are limited to a yearly pattern. At the other end of the scale their are patterns to when rain falls within an individual day. I'm not suggesting anybody can set their watch by the mid-day rain, but I think there are broad patterns in some places.

The problem with this specific question is proving it one way or the other. UK weather is influenced by several weather systems in such a complex way that any forecasts are difficult. Measuring small changes here would not be easy. The centre of larger continents have more stable/predictable weather, but they don't have the industrial pollutants to cause this supposed effect (!).

As said, the topic of _{<that g.w. thing>} is not the issue. I'd like to know if there is anything to substantiate or disprove the 'weekly' cycle. That really comes down to locating records fore some place with a generally stable weather/climate pattern, that also has a variable weekly pollution output. Probably impossible, but with CR4s wide readership maybe somebody will know something. If not, I may have to bury this poor idea <>.

Try Switzerland, Kris. They are really hot on links between air pollution and health. I was at a conference recently where the results of a week-long study comparing levels of pollution to traffic rates was done, comparing a busy trunk road with a park...significant difference seen week days to weekend.

I'm not sure if they've done work linking to weather yet...

If I find links, will post...off to run a rig now

That offshore data for Switzerland is hard to find..

They must have data for the Lac de Genève, a shore is a shore.

Can we plan a meeting on site?

I mentioned this near the bottom of my #4, but I don't think anyone believed me.

If ET was buzzing around Earth armed with a Doppler radar, I think he'd soon spot any pattern over major cities. I still think that the heat and pollution rising above major industrial areas must vary with any activity cycle. If it does, then maybe it's not such a giant leap to ask if pollutants act as a seed for rain clouds, and thereby a sub-pattern of rainfall is established. No doubt my detractors will say 'yes, but everybody is down the beach having a barbecue at weekends' , but my heretical pursuit will continue. Nobody ever found anything without looking, even by accident (you'd still have to look to see what the accidental discovery was).

Somewhere, I have references to people being able to spot ships over the horizon, by looking out for a cloud above them. That'll keep my doubters laughing. It's not the same issue I'm chasing , but it's not unrelated.

What about the effects of inversion layers?

In Zurich they found high morning pollution levels, corresponding to the rise in morning traffic, but then a steady decline in pollution levels throughout the rest of the day. They explained the lack of hometime pollution spike as being down to the fact that there was a greater dilution volume available in the evening than in the morning.

Any thoughts?

Sounds interesting, but I'm not really clued up on the behaviour of temperature inversions over Zurich (!). In my limited knowledge (from school long ago), inversions can (ie not always) occur at predictable heights and time of day. I see no reason why the inversion should not dissipate throughout the day allowing dispersal of pollutants. ie in the morning the smog is trapped by a lid, and late afternoon there's no lid. My Geography lessons were an awfully long time ago though. Never having been to Zurich doesn't help either. <Skegness childhood. very sad.>

I still think we need a site visit.

What? to Skeggie? 'Bout an hour's ride from here...

I was more thinking of Genève, nice in this period of the year.

But I will take it more pragmatic: next week I will check for rain in Frankfurt, Stockholm and Brussels.

The Swiss Air Force still uses the 3-engine Junkers 52. It's the only transport aircraft that flies slow enough to remain in the country!

Swiss traffic lights have a timer on the red aspect, to indicate when it times out, and a notice saying, "Für bessere Luft, bitte Motor abstellen" (Eng: turn your engine off; it stinks).

Since I usually work six days a week, I'm all for having a study financed by the Guvment, (say a couple million) to discover where the good area of the world is located in this cloud and rain cycle. Then I'm movin my butt and bike there.

There is an easy way to figure out if this is a perceived or real effect. Go the the NOAA site under regional climate centers they store all the rainfall data collected for weather stations. Use the map locator to connect to the data for a specific station near you (preferrably an older station). You can look at the rainfall history data and determine if there is a significant difference between early in the week versus later in the week. I suspect that is some areas of high particulate pollution forced high in the atmosphere, this may occur, but in most areas it is just perceived because rain on a saturday disrupts the planned trips to the beach, but on a monday just disrupts work for those who work outdoors 100% of the time.

Good points Guest. It looks like the only way I'm going to answer this is to track down the raw data as you suggest (though I may investigate the sources used for the studies I linked to first).

If I read your post correct, you seem to be saying that over (my example) large cities some effect may be possible. Also, that perception of rainfall (ie, people notice more when enjoying a day off playing golf etc) may give the false impression of a correlation.

Anything I find that can reveal more on this will be duly posted.

Don't think it's a pollution thing related only to weekends. I think it is covered by and demonstrates that "Murphy's Law" is in total control and Murphy is ALIVE and WELL.

As Del said -- Usually related to my whereabouts on any particular golf course.

Funny that this pop's up from time to time.

I heard of a German study, concluding the same.

See everybody ! Gwen heard of this as well !!

I new I didn't just dream it, there has to be some kind of answer to this out there. I'm now even more interested in seeing if their really is any hard evidence.

ER's Zurich thing and other stuff is why I'm sceptical about the 5days to cause the rainfall...obviously polution does have an influence...but why should it take 5 days to take effect? why not rains like mad after 1 or 2 days then settles down as the polution (and moisture) has been deposited ?

I'm not sure either, but maybe there is a critical point to seed rainclouds depending upon humidity. 0.00000000% pollutant may do nothing noticeable, but some higher figure would enable precipitation*. I shall have to check artificial cloud seeding.

* Warning : 100% pollutant means you may be standing on your head.

Kris, what you are looking for may be hard to find because it falls in between meteorology and climatology, and it might even be close to the realm of urban legend.

Meteorology is the study of weather primarily for the purpose of producing forecasts with a high degree of reliabilty for the next 3 to 36 hours. Climatology is the study of weather patterns for geographical regions over long periods of time.
What you are looking for is evidence of a long-term pattern of a short-term pattern recurring at a given period. It's not like looking for a needle in a haystack, because you can just use a magnet to draw out the needle. This is more like looking for straws of a given shade of yellow in a haystack with straws of all shades of yellow. You need to look at a lot of straws to find what you want.

I doubt seriously if there is a "global" pattern of increased rain chances on weekends. Deserts often go weeks or months without rain. In contrast, the ITCZ, the Inter-Tropical Convergence Zone, is a band of almost continuous thunderstorms near the Equator and is considered the Earth's meteorological equator.

I say this may be near the realm of urban legend because people don't pay much attention to the weather unless it affects their plans in a major way, or it suddenly turns dangerous, and their perceptions often depend on selective memory. If it rains during the week when most people are inside their offices, shops or schools, they don't pay attention to the rain or forecasts of rain unless they need to know if they have to carry an umbrella or something. But if their picnics, ball games, camping and boating trips get cancelled or interrupted, they not only notice, they never forget. If it happens 2 or 3 times in the spring, well, it sure seems like it rains every weekend. Of course, on the clear weekends, they shift focus to their plans and don't think about the weather.
When people discuss the weekends, they don't think about or mention all the times they had favorable weather, they just talk about what they did. But when someone mentions that they had several ballgames cancelled or called due to rain, then everyone talks about their own weekend activities cancelled because of rain. Next, everybody agrees that it tends to rain on weekends, whether or not the numbers bear it out. Thus, an urban legend could be born, if this thought spreads around far enough.

Thanks for the detailed post 3Doug. As you rightly say, there is a 'nether-world' type thing that exists between the definitions of weather and climate. The proposition does also smack of urban legend. It seems to be suggesting that there is a man-made pattern of influence, but it is buried within patterns of climate ( ie seasonal change) and daily change (ie weather). I see this as quite distinct from the oft debated global warming type thing.

Some of the links go so far as to suggest that hurricanes occur more in the afternoon. That's pushing it somewhat, since if a full scale rotational weather system has built up it's not going to be suddenly happening at a given time of day. That's something that occurs over days/weeks. The reports I looked at were saying that analysing data for some specific areas showed a pattern that cycled on a weekly basis. The lack of data to back that up makes me suspicious, though the hypothesized cause does seem to have some (albeit not much) merit. The primary question is , 'do pollutants rise above urban areas in a predictable way ?'. In other words, does more traffic and industrial activity happen during the week. If it does, then it would be reasonable to suppose more aerosol pollutants are rising above a given urban area (?). If so, then can these pollutants act in a similar manner to artificial cloud seeding. I think I'm correct in saying that rain drops need some kind of nucleus to form around. The lack of data presented in the links is infuriating. To make the case, I would have expected the researchers to have presented a nice graph mapping pollutant level alongside rainfall (for a specific city). What I'm really doing here is seeing if anybody knows of such data. I could search the web for ages, but I was hoping that with CR4s wide readership I might find somebody with first hand knowledge. Waaahhh.. The mechanism does have plausibility, but even if it does work ,the effect is probably insignificant compared to other cause of rainfall. As you (and others) quite rightly say, the perception of how much/when it rains skews any public reporting of rainfall. The first report I read, said that they had discovered an unknown phenomena simply because nobody else had though to look for it. Thought I'd do a bit of double checking....... The forecast is gloomy ! This thread has introduced some nice weather links and information though._{And all without getting into the dreaded global warming debate.}

Ask the Mythbusters.

They have all kinds of money to spend on it to figure it out.