So apparently an Italian Scientist got tired of getting wet in the rain and tried to figure out whether you should run in the rain or walk. Does the act of running force you to encounter more rain drops than if you were walking.
To quote Mac Golden..."Oookaaaayyyyy."
He's decided you should run. Unless the wind is blowing in the direction you are traveling. In that case you should jog the relative speed of the wind. If the wind is hitting your back at an angle then you should run slightly faster than the wind speed.
The physicists says its rather complicated. Read More.
Note: This picture is from Danny Santos II, an amazing photographer. Check his site and blog out here.