The unexplored region of the atmosphere that could help predict climate change

About 17 kilometers above the Earth's surface, the first layer of the atmosphere meets the second one. At a boundary called the tropopause, the troposphere ends and the stratosphere begins. Straddling this interface, for about five kilometers on either side, is a band of the atmosphere labeled, matter-of-factly, the "upper troposphere/lower stratosphere"—the UTLS.