National Geographic explorer and storm chaser Tim Samaras died in an Oklahoma tornado Friday, May 31, along with his son, Paul, and storm chaser Carl Young, his longtime collaborators. Samaras' research provided data to help researchers understand how and why tornadoes form. He had a long relationship with National Geographic, providing some of our most memorable videos of storms, including recently what might be the best, most complete video of a tornado being "born," in which Samaras describes a Kansas formation as it's happening. less