According to the search results, the top of the troposphere is called the tropopause. It is defined by the location where the temperature stops dropping with height. The troposphere is the lowest layer of Earths atmosphere, and most of the mass (about 75-80%) of the atmosphere is in the troposphere. The troposphere is bonded on the top by a layer of air called the tropopause. The tropopause is also where the stratosphere begins. Therefore, the answer to the question "what runs along the top of the troposphere?" is the tropopause.