Benjamin Franklin's most well-known contribution to weather science is probably his close encounter with lightning. But he also had a pretty famous brush with a tornado - in a manner of speaking. Here's that story.

Around this time in late August of 1755, Franklin was riding horseback in Maryland when, in his words:

"... We saw in the vale below us, a small whirlwind ... showing itself by the dust it raised ... its smaller part near the ground appeared no bigger than a common barrel ... I tried to break this little whirlwind by striking my whip ... through it, but without any effect."

What Franklin described here was not a tornado, but rather what we now call a dust devil. These tornado cousins don't descend from severe thunderstorms like true twisters do. Rather, dust devils are small whirls that form when strong sunshine heats dry ground, creating fast, rising currents of air. Just as winds blowing past a corner of a building can cause a whirl of leaves to form, winds blowing past hills and valleys can create spin in currents of rising air, and sometimes a dust devil is the result. Dust devils are typically just a few tens of feet wide, short-lived and harmless, with winds rarely exceeding 40 mph. You may have even seen one - they're much more common than actual tornadoes.