Do you get less wet if you run in the rain?

[TechBear_Seattle]

A friend of mine sent me this article from the BBC, dated Dec. 27, 2005. The full article can be read at http://news.bbc.co.uk/1/hi/magazine/4562132.stm

The summary, after going over the mathematical proof, is:

When it starts to rain, first identify the nearest shelter, and then run to it as quickly as you can.

This is remarkable, because that is precisely what most people do! The power of mathematics has finally given us the reassurance that, when we run for that bus shelter, store canopy or random shop (and start pretending to browse), we are getting it exactly right!

Bad news for Billy Whizz though - the equation shows that you get wet no matter how fast you run, with a minimum value of W = ρAD.

PS: If the rain is falling at an angle it is possible to decrease your total wetness by running in the correct direction. Unfortunately this may not coincide with the nearest shelter direction. If you are worried about this, we may be able to deal with it in a further instalment.

PPS: Alternatively, ignore the maths and get an umbrella.

[htuttle]

1. No matter the direction of the rain...

... I would still say that the less time you spend out in the rain, the fewer raindrops that will hit you (until you are soaked and it doesn't matter, of course).

[DS1]

2. Mythbusters covered this

They found that a brisk walk is the most beneficial, if you run to fast you run ~into~ all the rain and your front catches more than your shoulders would normally.

Then again, their measurement methods are crude at best.

[Viva_La_Revolution]

3. wtf?

If you run, as opposed to walking, you spend less time in the rain...

ergo - less wet.

Even factoring in variable weather conditions... how is this not true?

[BrainRants]

5. From the Mythbusters fanclub site:

http://www.mythbustersfanclub.com/html/exploding_toilet.html

Myth: Is it Worth Running in the Rain?

You will stay drier if you run in the rain rather than walk in the rain. Adam has a different theory: If you walk in the rain you will be in the rain longer, but only your head and shoulders will get wet. If you run in the rain, you will pick up rain on your entire front side.

The Experts:

Heather Joseph-Witham, folklorist, helps explain the myth. She says it is practical advice: You should run in the rain and you won’t get as wet as walking.

Richard Hunter, manager of Mr. S Leather, helps Adam and Jamie pick out some latex body suits.

Thomas Peterson and Trevor Wallis, National Climatic Data Center, tested the myth during a rainstorm. They measured out an approximately 100-meter course and waited until a rainy day to test the myth. They wanted to determine the relative difference between walking and running. After the test, they weighed their clothing. They determined that the runner was 40% less wet than the walker.

Action/Results: One of the most important aspects of this test is getting the right raindrop – the right size, the right velocity and an even spread. The test will consist of a 100-foot course with water falling a minimum of 60 feet. A raindrop will achieve a terminal velocity of 22 feet per second. The course will be built in an aircraft hangar. Sprinklers are placed every 6 feet along a 150-foot run. A fire hydrant is used as the water source. The water is put into a holding tank and dyed red for visibility.

To measure the amount of rain that lands on the Mythbusters, they will wear cotton coveralls that weigh 757 grams each. Under the coveralls they will wear a latex body suit to ensure that their perspiration isn’t included in the final weight. The course is set up to produce 2 to 3 inches of rain per hour. Jamie and Adam each will go through the course 4 times, once walking, once running, once walking with fans used to simulate wind and finally once running with fans used to simulate wind.

When the coveralls are weighed, the ones worn when they walked turn out to be lighter than the coveralls that they ran in. It is better to walk in the rain than to run. Myth busted.

[unblock]

11. SPRINKLERS????

unless the sprinklers were mounted overhead, so that the rain comes straight down like real rain, the experiment is bogus.

if the sprinklers were on the ground and shot water up and it comes down at an angle, then this misses the entire point of the difference between walking and running. with overhead rain (straight down), running presents your front to rain, whereas walking doesn't (or does so to a much lesser extent). if the rain is coming at you at an angle, then your front (or side or back) is already presented to the rain, and running may present more or less body surface to the rain, depending on the angles and the timing.

MYTH BUSTERS BUSTED!

[BrainRants]

15. The sprinklers were mounted above.

As I recall, they used an old airplane hanger with an elaborate sprinkler system they built suspended from the ceiling and colored water to show the spread of water on the white overalls.

I'm no scientist (well, I'm a computer scientist) but they do a pretty good job applying the scientific method to prove or debunk myths. They're pretty careful about measurements too. As I recall they wore one of those kinky rubber suits underneath the coveralls to avoid any sweat or absorption of the water.

I think they have a team that sits down beforehand and asks "What kind of email are we going to get shooting holes in our methodology?" then they set out to fill the gaps.

[TechBear_Seattle]

7. I think the question is: can it be *proven*

Read the article :bounce:

[liberal N proud]

4. By reason - The less time spent in the rain would be less rain drops

[unblock]

8. you're missing the complicating half of the problem

running = less time in the rain, true enough.

however, assuming the rain is coming straight down and the top view of your body is smaller than the front view, then when you run, you expose the front of your body to rain as you run into falling raindrops, in addition to the rain that falls on your head anyway. the faster you run, the wetter you get for a given period of time in the rain.

so the trade off is, is less time in the rain (good) a bigger factor than exposing your front to more rain while running (bad).

[unblock]

6. ah, memories of high school physics....

ideally, the rain is at an angle, and you can run whilst leaning into the rain, presenting only the top of your head to rainfall. this is ideal, assuming you have a reasonable choice of shelters.

[RagingInMiami]

9. But if you happen to walk out of a building into the rain after it's been

raining a while, and everybody is just hanging about waiting for it to stop, and you decide to make a run for it anyway.

Then Murphy's Law dictates that you must stomp in every single puddle on the way to your car, causing your feet to sink into 12-inches of water, soaking your shoes and socks and turning you into a prime candidate for pnunumonia, and leaving both pant legs splattered with rain water.

[proReality]

10. Running=splashing=wetter in lower extremities. Walk, don't run. n/t

[rman]

18. Depends on the amount of standing water - avoid pools and puddles

But we already knew that as well.

[bluerum]

12. Neglecting variations in cross section, the main considerations

here are what I will call the rain flux (the density of raindrops per unit volume per unit time) and the amount of time you spend in the rain.

Yes, the angle of the rain relative to your cross section can be rolled into your calculation but I think this ends up being a simple proportioning factor. You will always get hit by the rain, no matter what the relative angle. Lets assume a constant cross section of head and shoulders and parts of your legs and feet being exposed to vertical rainfall.

Assuming that the rain flux is reasonably constant, the main factor in determining how wet you get is the amount of time you spend in the rain.

If you change the cross section exposed to a uniform flux you will of course become wetter in proportion to the change in cross section.

[On the Road]

13. Try This Thought Experiment:

If you walk very, very slowly and take a half hour to reach the shelter, you'll get a lot wetter than you would if you spend a minute running in the rain, including however many raindrops you ran into. I think there's a problem with the BBC's model.

[Bill McBlueState]

14. they cover that, don't they?

In their analysis, your wetness is described by a term that's proportional to time plus a constant.

[MrMonk]

16. I couldn't say whether running or walking makes you wetter

(in the sense of the mass of water that accumulates).

I do know that when you run, a larger area of you gets wet, and you *feel* wetter.

[silverweb]

17. The best solution.

The best solution is to run in a zig-zag pattern. Some call this technique "evasive maneuvers." Others call it "dodging raindrops."

PS - Unless you're a wicked witch, you won't melt. It's only water, anyway.

:rofl: