troposphere
Meaning
the lowest layer of the earth's atmosphere, extending from the earth's surface to a height of about 6–10 km (at the poles) to about 16–18 km (at the equator), within which nearly all weather phenomena occur.
the lowest region of the atmosphere of a planet, especially the part of the earth's atmosphere where temperature decreases with altitude.
Structure
Usage
commercial aircraft typically cruise just above the troposphere in the more stable stratosphere.
temperature generally decreases with altitude in the troposphere.
most of the atmosphere's water vapor and clouds are found in the troposphere.
Etymology
the term 'troposphere' was coined in the early 20th century from greek roots to describe a specific atmospheric layer. the element 'tropo-' refers to turning or change, alluding to the turbulent, mixing nature of this layer where air currents turn over and weather changes occur. '-sphere' denotes a spherical shell, fitting the conception of the atmosphere as concentric layers surrounding the globe. thus, the word's literal meaning, "the sphere of change," perfectly captures its defining characteristic as the dynamic, weather-active region of the atmosphere.
Analysis
tropo originates from greek 'tropos', meaning "a turn, change, way, manner". sphere originates from greek 'sphaira', meaning "ball, globe". in this compound, 'tropo' describes the characteristic of the layer, and 'sphere' denotes a spherical layer or region.