Atmosphere of Earth (see the temperature section, below). Because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. From highest to lowest, the five main layers are: The exosphere is the outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere). It extends from the exobase, which is located at
The Outermost House retreat to visit whenever he could, but soon found he did not want to leave. "[A]s the year lengthened into autumn, the beauty and mystery of this earth and outer sea so possessed and held me that I could not go," he wrote in "The Outermost House". For the next couple of years, Beston would come and go from his dune refuge, keeping extensive notes on his observations of life on the beach. His meditation on surf ("The Headlong Wave"), experiences on the winter beach, and his view of life after his beach stay were molded together into one "Year