Clouds and Vitamin D

As I pulled the splinter from my chest this morning, I wondered if the rainy cloud cover in yesterday's workout meant that I didn't get my daily dose of vitamin D. I did the workout shirtless, hence the splinter from no-arm Turkish Getups with a log on my chest, Fifth-Ape style. Luckily, I found this article in the NY Times that says clouds reduce UVB, the radiation needed to make vitamin D, by about half, which means that I got plenty.

http://www.nytimes.com/2008/04/15/science/15qna.html