walk or run through rain?

your surface area doesn't change when you're walking so the main criterion is time spent exposed to rain.

thus, running is best if you're running to a dry spot.

"Mythbusters" checked this out, but I cannot remember the outcome of their experiment.

My chemsitry teacher told me this one. he went to some science confernce and they talked about some experiment they did to test that exact question. long story short walking is better.

Interesting thing though, the scientist who did the experiment was at the conference and when a group of them were caught out side in the rain, instead of walking he ran! just goes to show, doesnt matter what you know if you dont use it!

The frontal cross section will absorb all the water in that cross section along the route regardless of how fast you go (assuming constant rain density). Imagine, instead of going instantaneously, you're going unbelievably slow. You will still hit drop in front of you, just less freqeuntly. There is a linear relationship between frequency of horizontal drops and speed.

But as Cecil points out, if you walk you'll get a lot more drops on your head and top of your shoulders, so you should run.

Also, what you say is only true if the rain is coming straight down. If there is a wind at your back and you move at the same speed as the wind, you won't get any drops on your front or back. If there is a headwind then the number of drops in your path to shelter increases with time, so you should run as fast as possible.

i stole this from Rogers Answer Man:

Let's look at the problem: No matter if you walk or run, rain will fall on your head. This is unavoidable. If you run, you will spend less time in the rain, thus less total rain will fall on your head, and you will remain drier. However, if you run you will also be running into raindrops — that is, you will be hitting them with your chest as you proceed to your destination. If you walk, you cover less horizontal ground each second, so you run into fewer raindrops per second. (Looking at the extreme case, if you stand perfectly still, the only rain that will hit you will be the rain that falls on your head. However, you won't get out of the rain until the rain stops, so this usually isn't an option). Is it worth exposing your chest in exchange for getting fewer raindrops on your head?

Let's establish an "ideal" rain shower. There's no wind so the rain falls straight down, and the rain falls at a constant rate and density on every part of your path.

Clearly, the amount of rain falling on your head from above is directly proportional to the amount of time you spend in the rain. For instance, if you're out in the rain for 10 seconds and get hit by 100 drops, then if you're out for 20 seconds you'll get hit by 200 drops.

But what about the horizontal component? It turns out that this is directly proportional to the distance travelled. While it might seem that running exposes you to more rain on the front of your body, it really doesn't. You are exposed to the same amount — it just happens more quickly.

With our idealized, constant rain, the density of raindrops in front of you is always the same; some of them are falling out of the frame, but new ones are coming down to replace them. So whether you walk through the rain or run through it, you will pass through the same volume of water. Imagine if you could freeze the scene with the rain suspended in the air — the water you see in front of you is the water you have to walk "through," and whether you move through it slowly or quickly, that's the amount of water you're going to hit.

So the vertical component of the rain is proportional to the time spent in it, while the horizontal component is proportional to the distance travelled — and the distance is the same in both cases. Obviously, if your sole motivation is to stay dry, it always makes more sense to run.

If you factor in wind, there are some slight changes to be made (if the wind is at your back, it's best to move at the same speed as the wind — not slower or faster), but running is inevitably the drier method. There's an amazing calculator here that shows you exactly how much drier you will be if you run. It lets you factor in wind speed, the speed and angle of the rain, the size of your body, and the distance to your location. Plug in some numbers and see how it comes out.

There are a few other issues you might want to consider — if you're travelling through standing water or puddles, running might cause splashes that walking won't, and if you're running you might be more likely to fall and get really soaked. But overall, running is the best method.

Sources: Seattle Times, Ask Dr. Math, Great Moments in Science

What an arguement. That was great.

I saw that calculator thing online a while ago, and yeah, you can punch in your measurements (height, weight, chest measurements, span of shoulders) speed at which you're moving, the inches per hour of rain, the windspeed, size of the drops, literally every variable in the equation, and it punches out the exact volume of the water that you will encounter, and yep, the faster the speed you move, the less rain will contact your person.

WOW, this has to be the most intelligent non-Bush-related thread EVER! Congratulations to anyone that reads it. I've thought about this very question for 18 years and what you've all said so far makes sense. If we define wetness as: The amount of raindrops that hit your body, then moving at 1 M/S or 10 M/S you will still catch the same amount of drops per second, all else being equal, PERIOD! The running part only should come into play with regards to form. Swing your arms and have a big leg kick, you become a bigger target for drops. Tuck your arms in, and walk straight-up and you're a smaller target. More of your body will get hit by drops if you run, but the same total amount of drops. Truth be told, don't run to get out of the rain, run in the rain to run in the rain.

Maybe you misspoke... it's not the same volume of water per second. The amount that hits the top of your head is the same; the amount that hits your front increases with your velocity.

This reminds me of something i noticed a couple years ago. At home, the awning of my apartment buildings and most of the ones near it jut out from the building to the street. They slope down towards the sidewalk, so that all the rain that lands on them falls onto the sidewalk, not onto the street. The question then is does walking under an awning keep you dryer? The answer is no, the same volume of water hits you, but bigger droplets hit you as they fall from the awning, so maybe you get a little wetter.

But the volume that hits your front is constant over the same distance, regardless of speed.

I thought about the same thing today as I was waiting for the bus as it was pouring rain. Do I stand under the tree to stay dry? But by that time, it had been raining for so long that the leaves had been saturated, and larger drops were falling from the leaves. So at what point do the leaves get so full of water that the water starts falling off the leaves? And is this amount of water the same as that which is raining? Can you figure out how long this will take by estimating the number of leaves and size to approximate the total surface area of leaves and the water they will hold? Ah, the questions that keep me awake at night.

I disagree with what he says.

1. If you stand perfectly still, the only rain that will hit you will be rain on your head - this would only happen in a very very small number of cases, where there's no wind, so is not representative enough to be used to try and solve the problem.

2. He says you're exposed to the same amount of water, but 'obviously' if you want to stay dry, it makes more sense to run. Surely that contradicts itself?

No Wind

Run as fast as possible.

Headwind

Run as fast as possible.

Crosswind

Run as fast as possible.

Tailwind

Run at least as fast as the wind. Whether you should run faster than the wind depends on the wind speed.

The easiest way to understand the cases with wind is to consider the extreme case of the rain moving horizontally.

There are factors many are forgetting such as sweat and safety. If you run, you will start to sweat, and depending on the situation that may not be good. Second, what if there's lightning? I'd rather get to the safety of the building quickly even if I do get wetter. Not having done a run/walk experiment myself, I venture to guess that the difference in wetness between walking and running is small enough that these other factors are more important. Here's another consideration: Suppose your car is 500 meters across the lot and it's pouring. You're going to be soaked by the time you get to it whether you run or walk. You can't be "more soaked" even if 20% more rain hits you along the way.

Besides, you could just watch the morning news or check your favorite Internet weather source and bring a small umbrella with you if the forecast predicts rain.