As a male, it seems I am destined to be good at focusing on one thing but terrible at multitasking.
If I'm driving and talking with someone at the same time, I'm not likely to make turns when I'm supposed to because I usually end up focusing on the conversation.
But yes, there's something about the rain that is calming. Rain is life returning to the desert that I live in. The plants give off a smell wonderful and unlike any other after a rain, but I've experienced it all across the US in the places I have been. I've traveled more than most by plane and by car, and that has been to more places than I have traveled with the military (and I jumped out of planes for them too). The rain makes a steady, soothing beat that is wonderful for all manner of free thought or no thought at all. You just.... listen.
The other place I enjoy is in the water itself, in the pool. If you understand it, motion is fluid, motion is liberating. It's like flying but instead of the air, you're in the water. You have so much control, if you know how, and there isn't much noise to interfere. In the water, you are far freer of gravity's oppression- it's like being weightless. You might not get the speed of the shark, but you have far better directional control and sometimes you just want to drift away...