The stratosphere (/ËstrÃ¦tÉËsfÉªÉr, -toÊ-/) is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. About 20% of the atmosphere's mass is contained in the stratosphere.
The chainsaw is a highly effective and efficient tree and branch cutting power tool. It works with an engine, referred to as a power head; powering a metal chain, driven by a centrifugal clutch, with a chain moving around a groove in the guide bar at fast speeds.
Chainsaw - Safety. 1  Despite safety features and protective clothing, injuries can still arise from chainsaw use, from the large forces involved in the work, from the fast-moving, sharp chain, or from the vibration and noise of the machinery.