Drops are falling vertically in a steady rain. In order to go through the rain from one place to another in such a way as to encounter the least number of raindrops, should you move with the greatest possible speed, the least possible speed, or some intermediate speed? (See ''An Optimal Speed for Traversing a Constant Rain, by S. A. Stem, American Journal of Physics, September 1983, p. 815.)

At first it is qualitative to think that running in the rain would make fewer raindrops to fall on your body and as a result you will get less wet. However a closer inspection could show how far the reality goes against our intuition.
When you run in rainfall, the raindrops which nearly missed you earlier also get the chance to hit your body and therefore the number of raindrops which hit your body increases. This make you more wet than you anticipate.
Also, traversing the rain with least possible speed increases the time of exposure of body in the rain and also accounts for large number of raindrops hitting the body.
Therefore, one should walk with intermediate speed while it is raining.