why does it rain more often at weekends?

Question

i noticed this phenomenon in my countryi wonder if it has anything to do with the global warming.

Answer 1

Ya, it seems that there is something to the "more rain on the weekend" thought.

A recent study published in the Journal Nature is report on in the following article:
http://www.scienceagogo.com/news/19980706131634data_trunc_sys.shtml

"The study, published in Nature, suggests that rain is most likely to occur along the US Atlantic coast on the weekend and the weather is most likely to be better on a Monday, Tuesday or Wednesday. The most obvious culprit is the "natural" cloud-seeding effect created by the massive drift of East Coast pollution, which also follows a well defined weekly cycle."

Here is another report about a study that was done in 1998:
http://www.weathernotebook.org/transcripts/1998/11/09.html

"Dr. Randall Cerveny: "We find that along the Atlantic Seaboard, rain tends to follow a very distinct seven-day cycle where it’s rainier on Saturdays and somewhat drier on Mondays."

That’s Dr. Randall Cerveny, a climatologist at Arizona State University. He recently authored a study that statistically showed rain to fall more often on the weekend than on other days of the week. Now nature doesn’t work on a 7-day cycle, that’s something we humans created, so the thought is that something else we’ve created—pollution—may be causing this weekend dreariness:

Dr. Cerveny: "Ours was a statistical study and so we don’t have firm cause-and-effect relationships. But we’re suggesting that the pollution traps heat and one of the fundamental ideas in meteorology, of course, is that hot air rises and if it rises, it’s more likely to cause clouds and precipitation."

"Think of it this way. During the workweek, pollutants are being released into the air. Well, that pollution builds and builds during the week and when the weekend hits, there is just a little extra kick, and…you have another weekend of rain. "

So, at least in the eastern US, the rainy weekend patterns, and Murphy's Law, seem to hold.

Answer 2

Yes, it is global warming. Very few people have been quick enough to pick up on this pattern. They are too busy looking at pine cones and ice cores to see the obvious as you have.

What you won't find out in the news is that the temperature of the earth increases from Monday until Friday because of the increased use of CO2 producing products. This heats the earth up and evaporates more water into the atmosphere. Then, starting on Friday afternoon, the temperature begins to fall as loads drop off. Then the cooler atmosphere can hold less water and the vapor condenses to rain and falls back to earth.

Crazy idea? Maybe, but no more inaccurate than any other answer you will get for this question.

Answer 3

It doesn't. It's observation bias. You care more about what the whether is like on weekends so you perceive that it's raining more often. Day to day fluctuations of the weather have little to do with global warming which is a long-term phenomenon having to do with climate change. Climate and weather are not the same thing. What climate can do is alter the overall structure in which weather takes place causing some areas to be more prone to rain, drought, or more intense storms (more warmth means more energy for storms). But it in no way will make it more likely to rain on a Saturday than a Wednesday. What it is doing is rapidly altering the system making it even more difficult to predict what the ramifications will be.

Answer 4

Lots of interesting answers here. My question first of all would be do you live in a city. If so I think others are correct to imply pollution M-F is responsible (i don't know about the moon and water evaporation...sounds interesting but unlikely). I agree with somebody else when they say this is a weather issue, not a climate issue.
Clouds are formed by water condensing on particles in the atmosphere. Let's assume for now that the amount of water (i.e. the physical number of water molecules) is constant all week long. During the week when there are more particles in the atmosphere and if the conditions are right, clouds will form. For them to produce rain, enough water must condense on each particle to 'activate' it, that is they become large enough to fall as rain. If there are lots and lots of small particles from pollution then the amount of water in the atmosphere is spread more finely among all of the particles and they are less likely to be activated, this may result in a hazy persistent cloud layer about cities. At the weekend, when there are fewer particles, the same mass of water condenses onto much fewer particles and is more likely to form rain droplets.

Of course, there differences in water vapour throughout the week change depending on atmospheric conditions. I would be surprised if you noticed more rain at weekends just be casual observations. If you have records of physical measurements of more rain at the weekends then you may be able to see if the effects of pollution are causing this phenomena.

Answer 5

You just notice it more on weekends.

The truth is, it rains more often immediately after the full moon. So if your weekend falls on this event, it'll probably rain. This is because the full moon can account for 25% of the nighttime evaporation (or so says my professor). More humidity = more chances of rain.

bkc99xx - maybe that''s heat island you're describing, not so much global warming? but it makes sense, good call. =)

Answer 6

The east ans south east of england have a dry climate and are presently affected by an valid drought. The west and north west of the rustic are plenty wetter, so i assume the developers only paintings in the rain. It not often rains 5 days a week even nevertheless

Answer 7

I actually read in the paper a few weeks ago about a theory thatis something to do with all the traffic during the week and the fumes build up then stop at theweekend which causes a downpoor or something.

this article briefly touches on the subject

Answer 8

Because people who work m-f put out more pollution and the air cleans itself on weekends by raining.

Answer 9

I'm got sure that it does. However, I think we notice it more on the weekends because we have free time and get annoyed that we can't make use of it outside.

Answer 10

You probably just notice it more at weekends because you out and about rather than during week when at work!