[Reading Science] To Get Less Wet in the Rain, Should You Run Instead of Walk?

If you don't have an umbrella on a rainy day, is it better to walk or run to get less wet?
[Photo by the movie "Classic" still cut]

[Asia Economy Reporter Kim Jonghwa] When it suddenly rains and you don't have an umbrella, people instinctively run. Those with a relaxed personality or who have given up avoiding the rain just walk. Is it really better to run instinctively to get less wet?

Some argue that walking actually gets you less wet, while others claim running does. The former argue that when walking, you only get hit by raindrops falling from above your head, but when running, you get hit by raindrops both from above and in the direction you are running, hitting the front of your body.

On the other hand, the latter claim that because the exposure time to the rain is shorter, you get less wet overall. So, whose claim is correct?

The amount of rain a person gets depends on their height and body width, wind direction, and raindrop size. Until the mid-1990s, European scientists published research suggesting there was little difference between running and walking in the rain, so many people believed that.

According to a paper published in the European Journal of Physics in 1987, running is better if the distance is short. Even then, it was estimated that running gets you about 10% less wet than walking. In 1995, a British scientist argued that if you move at a speed faster than 3 m/s in the rain, there would be little difference between walking and running.

These two scientists concluded that such a small difference would hardly be felt in practice, so there was no need to run even if it was raining. However, since the 2000s, research results directly contradicting these claims have begun to appear.

Dr. Thomas Peterson and Dr. Trevor Wallis, climatologists at the U.S. National Climatic Data Center, rebutted, saying, "Previous studies set walking speeds too fast and ignored variables such as wind effects and leaning forward while running, so their results are not objective." They then conducted experiments by running into the rain themselves.

The two wore the same clothes and moved 100 meters, with one walking and the other running. Afterwards, they weighed the clothes worn by each. The clothes worn by the walker weighed 220g when wet, while the runner’s clothes weighed 130g, showing a difference of about 90g.

This proved that the runner got about 40% less wet than the walker. In 2012, Italian physicist Dr. Franco Bocci gained attention by arguing that "you must run at an appropriate speed." Dr. Bocci explained, "The actual amount of rain a person gets depends on various factors such as height, body width ratio, wind direction, and raindrop size."

He also argued that the optimal speed should be calculated considering these factors. Can you make such calculations while running in the rain? Dr. Bocci’s answer is simple. "To avoid the hassle of calculating the cosine angle between the path and wind direction, I present a general formula," emphasizing, "Run as fast as possible."

He added, "Generally, it is best to run fast regardless of wind direction, but if the wind is blowing from behind, it is advantageous to run at the same speed as the wind." How to calculate the speed equal to the wind? I will just run fast.

In any case, recent scientists argue that as long as you keep moving, whether walking or running, the same amount of raindrops fall on your head, so the best way to get less wet is to get out of the rain as quickly as possible.

However, this theory applies to short distances of a few hundred meters at most. You wouldn’t be traveling a long distance in the rain using public transportation, right? It’s raining. If you don’t have an umbrella, run. You will get about 40% less wet than walking.

This content was produced with the assistance of AI translation services.