In the rain: Usually run, but sometimes walk

Cecil's Columns/Staff Reports
1

Regarding the question of whether someone stays drier in the rain by walking or running, most web sources say you’re drier if you run. Usually you are, but sometimes not.

One source said that the exceptioin is when the wind has a component blowing from behind. That’s correct. That person said that, with that kind of a wind, you’re better off to limit your speed to the wind’s speed. Not necessarily so.

Here’s the complete answer:

Assuming that you don’t lean forward when you run:

Usually you’re drier if you run. But if the wind velocity has a component from behind you, and that component speed exceeds some lower limit (that limit depends on your dimensions, the wind’s downward speed, and the crosswind if any), then you’re drier if you limit your speed to the wind’s speed.

If there’s any crosswind to speak of, then that lower limit might be in the running-speed range rather than in the walking-speed range, in which case it can’t be said that you’re drier if you walk.

If the wind is from behind, but doesn’t reach that necessary lower limit, then you’ll be drier the faster you go. Likewise if the wind has a component blowing from the front instead of from behind. And of course if it’s blowing entirely from the side.

And of course if the rain is a slow-falling small-droplet drizzle, that lower falling speed decreases the lower limit of the wind’s from-the-rear component speed needed to make it so that you’re drier if you limit your speed to the wind’s speed.

If you’re skinny, with a small maximimum back-to-front dimension, that lowers that necessary lower limit for the from-the-rear component speed needed to make it so that you’re drier if you limit your speed to the wind’s speed.

So, the short answer is that, if you don’t lean forward when you run, you’ll usuallyb e drier the faster you go, but there are conditions under which you’ll be dryer if you limit your speed to that of the wind.

Say you’re 6 feet tall, and about .9 feet back-to-front, and the rain is falling at around 14 feet per second, and the wind velocity has a from-the-rear component of 3 mph. You’ll be drier if you limit your speed to the wind’s speed, 3 mph. To tell the truth, I didn’t re-check that calculation. But I wanted to say something concrete.

2

Welcome to the Straight Dope Message Boards, replying, we’re glad to have you with us.

When you start a thread, it’s helpful to other readers if you provide a link to the column you’re talking about. Saves a lot of search time and helps keep us all on the same page. In this case, it’s Which will keep you drier, running through the rain or walking?

No biggie, you’ll know for next time, and, as I say, welcome!

3

Wow, does that bring back memories! That was one of the first SD columns I read, in the Boston Phoenix, all those years ago.

4

MythBusters tested this, but alas, I don’t recall the outcome.

5

Mythbusters found that you would be drier walking, but their experiment was flawed, since they only collected and measured rain which hit the body, not that which hit the head, and it’s the head drops which should theoretically give running the advantage.

Also theoretically, it should be noted that while exactly matching speed with the wind would typically be advantageous, the matching has to be exact. If your speed is even slightly different, you’d probably be better off at a flat-out run.

6

It’s been a while since I saw the episode, but didn’t they wear white hooded jumpers? The hooding would have collected the “head drops”, I would think…

7

Hm. I remember noticing the lack of hoods at the time I saw the episode, but I can’t conveniently check now. Does anyone have them recorded?