Let’s imagine that you are walking outside, when rain clouds catch you by surprise and suddenly pour down on you. Assuming that you have no umbrella or anything to cover yourself with, is it best to run back home or walk back? Or to elaborate, should you walk and spend more time in the rain, or should you run, which means you will run into rain sideways?
There are two ways you can get wet in the rain: it will either fall on top of your head, or you will run into it from the side. The amount of rain that falls on your head is constant whether you are walking or raining, as the entire field you are travelling through is full of raindrops. Therefore, one would naturally think that running would not add much benefit as you run into more rain by moving faster, as you essentially hit a wall of raindrops.
But this is not true. No matter how fast you travel, the amount of rain you hit sideways is constant. The only variable that affects the amount of rain you hit sideways is the distance you travel. This is because the amount of raindrops in the space between you and your destination is constant.
Summarising this, the wetness from rain you receive is:
(wetness falling on your head per second x time spent in rain) + (wetness you run into per meter x distance travelled).
Since you cannot really change how far you are from your destination, the best way to minimise getting wet is to run as fast as you can to minimise the time you spend in the rain.
Then again, this is only the most practical option to keep you dry. If you are feeling particularly romantic or blue, then feel free to stroll through the rain, savouring the cold drops on your face (or wallow in the sadness that is your life).
(Here’s a very good video explaining the maths/science of it all: http://www.youtube.com/watch?v=3MqYE2UuN24)
