To run or not to run

Had a lovely meal at a Japanese restaurant in Brixton today, Fujiyama. Hot miso soup, crispy tempura, thick udon noodles, vegetable skewers, chicken katsu don and endless cups of jasmine tea. They also now serve sushi and sashimi, but I didn't order any as most of our group were vegetarian and I didn't want to repulse them. I think I've found my new favourite Japanese eaterie though: the food was so fresh and the servings were big. I'm happy, because I need to get out of my Tokyo Diner rut.

Because we got caught in a rainstorm, most of us ran to the restaurant and then wondered why we had bothered. So began debate over that perennial scientific conundrum: who gets wetter, a runner or a walker?

All things being equal (distance travelled, rain intensity, rain angle, body shape and size), you would assume the walker gets wetter because more raindrops hit the top of the head. The runner exposes less of the head to the rain, but more of the front of the body.

So surely the deciding factor has to be time. The runner gets hit by less rain than the walker because she spends less time in it. But then what about the runner's increased likelihood of splashing? (The question is who gets wetter, not who receives the most numbers of raindrops as they fall.)

All things never being equal in real life, for walkers and runners alike: the model can't account for splashing in puddles or getting sprayed by passing cars, for changes in wind force and direction, or for the fact that rain never falls perfectly vertically, that rain doesn't fall at the same velocity, that a person doesn't move at a constant speed, that people don't move at the same angle, and an endless number of other variables.

It's fun wondering though. My tips? 1. Always run, the exercise is good for you. 2. If you insist on walking, carry an umbrella, you dope. 3. Stay inside, have another beer and wait it out.

Related links:
+ Thomas Peterson and Trevor Wallis' research for meteorological journal Weather into who gets wetter, a runner or a walker.
+ The physicist who did the math and calculated a walker gets 40% wetter in the rain.
+ Running-in-the-rain calculator

Other links today:
+ The Givers. Using the Web to promote tsunami relief.
+ Spiders watch their diets too