From similarity and differences of morphological, biochemical, cellular characteristics, biologist have constructed 'phylogenetic (evolutionary) trees' (who is most closely related to who, analogous to a family tree)
In the United States, lightning routinely kills more people each year than tornadoes or hurricanes. Tornadoes, hail, and wind gusts get the most attention, but only lightning can strike outside the storm itself. Lightning is the first thunderstorm hazard to arrive and the last to leave.
Tornadoes are a weather enigma. To be such violent storms, most don't result in death, and those that do result in death claim few lives. (For example, in 2015, tornadoes claimed a total of 36 lives for the year.) But this isn't always the case.