Earlier this week I was ice fishing on a lake in northern Maine that just happens to be under the flight path of many airplanes going to and returning from Europe. Being a bit of an aviation geek, I enjoyed guessing at the model of the planes overhead. I could quickly identify 747s, A380s, and A340s because they leave behind four contrails while twin engine jets leave behind only two contrails. I share that story because Reactions has a new video that explains how jet contrails are created.