Waves apparently aren’t restricted to large bodies of water or the stands at sporting events — they can happen, albeit rarely, in the sky as well. When air is pushed up into a more stable layer of atmosphere, it can cause a ripple effect, just like tossing a rock into a pond. For a gravity wave to occur, there must be a disturbance in the atmosphere, such as an updraft of a thunderstorm. Recent studies indicate that gravity waves have the power to concentrate and intensify tornados, so if you’re lucky (or unlucky) enough to view the undulating cloud formations firsthand, I’d suggest seeking shelter soon after! Iowa would be a good place to start the hunt.