Rainstorm, Walk or Run?

Running adds a horizontal component to the rain and soaks your front, where as walking soaks you mainly on the top.

Myth Busters did this once and weighed the clothes to find total water content for walking and running. Running was definitely worse!

Several years ago a British Uni did wonder about this topic. They discovered the variables--the rate of movement(Walk-Run), distance covered and certain "rain rate". There was for each condition a 'middle point' that it didn't matter whether you ran or walked you will get wet the same amount. Obvious

I would go with the Myth Busters result. Sometime note the difference in the amount of water on your windshield while stopped vs 45mph.

When running, you increase exposed area and hence soaking rate, true if it's raining vertically. But, conversely, it might be the case that the rain is slightly inclined so that "walking" increases the exposed area. Anyway, when running, you reduce exposure time if the distance is constant. If you take it to the limit, somebody with infinite velocity will not get a bit of a raindrop, but somebody with zero velocity will soak infinitely. It depends which factor becomes more dominant, but I would always count on reducing exposure time, i.e. run.

According to Discover magazine, Alessandro De Angelis, a physicist at the University of Udine, Italy, calculated some years ago that "a sprinter racing along at 22.4 miles an hour does get less wet, but only 10 percent less wet, than a hasty stroller (6.7 miles an hour)." Conclusion: running isn't worth the trouble. First the theory. Divide the raindrops hitting you into two categories: (1)head drops, which fall from above and would hit you even if you were standing still; and (2)chest drops, which you run/walk into and which wouldn't hit you if you were standing still. The number of head drops is strictly a function of how long you're out in the rain; if you run, fewer head drops. The question is whether the allegedly larger number of chest drops you get when running outweighs the definitely larger number of head drops you get while walking. If we ignore aerodynamic effects, you can demonstrate mathematically (not that I plan to!!!) that while you'll collect much fewer head drops running rather than walking, you'll get exactly the same number of chest drops, regardless of the speed at which you travel. Bottom line: you'll be a lot wetter if you walk. My guess is that the number of drops is exactly proportional. If you're out twice as long, you get twice as wet. One obvious caveat.......If enough rain falls on you, whether because of the intensity of the rainfall or the distance you have to travel, eventually you'll be thoroughly soaked. After that it doesn't matter whether you run or walk; you're as wet as you're going to get. So the preceding applies only to relatively short sprints through less-than-torrential downpours. My advice?.......always run--if nothing else you could use the exercise..........I really have too much time on my hands :-)

Another way to think about this: As you move from point A to point B your body sweeps through a constant volume of space. The number of raindrop that hit you from the front (the chest drops described above) will be equal to the number of raindrops in that volume. Let's call that number of raindrops X. Note that it does not matter that the raindrops are moving vertically through the volume that you sweep out - the volume remains the same. (If you are in doubt, consider the area of a parallogram.) As you move from point A to point B you are also subject to raindrops that hit you from above (the head drops described above) Let's call this number of raindrops TY where Y is the number of raindrops that hit you from above per second and T is the number of seconds that it takes you to move from A to B. The total number of raindrops that hit you becomes X + TY. Minimize this function by minimising T or more simply put - run, run, as fast as you can.

I once heard an interesting theoretical consideration of this problem. It consisted of two mental experiments at the extremes of the problem. The first consideration was running from point A to point B at the speed of light. At that speed, the water encountered by the runner (and assumed absorbed) was equal to the raindrops in the "tunnel" or volume formed by the runner's cross-section and the length from A to B. At the other end of the scale it is assumed that the runner goes infinitely slow. The water absorbed is that falling from the top for an infinite length of time. You can't get wetter than infinitely wet!