I have taken these photos numerous times since 2010 and that shadow could be all the metal particulates reflecting back at the sun ,but the other particulates like fluoride? to hold the trail together could be shading it. the sun angle and sky placement might be part of it also, because the shadow doesnt always show up. Thats my thoughts on the shadow showing up sometimes, but not always. If it is a fake led sun, it wont be as high as we think it is. Yes, I said fake sun, becuase sometime during Obama it became a cool led luer ligh sun except sunrise and sunset.