Atmosphere of Earth that gas. The stratosphere defines a layer in which temperatures rise with increasing altitude. This rise in temperature is caused by the absorption of ultraviolet radiation (UV) radiation from the Sun by the ozone layer, which restricts turbulence and mixing. Although the temperature may be at the tropopause, the top of the stratosphere is much warmer, and may be near 0 °C. The stratospheric temperature profile creates very stable atmospheric conditions, so the stratosphere lacks the weather-producing air turbulence that is so prevalent in the troposphere. Consequently, the stratosphere is almost completely free of clouds and other forms of weather.
The Songs of Distant Earth would have to carry to first accelerate to the speeds required to travel such great distances within an acceptable time, and then decelerate upon approaching the destination. This limitation is overcome however with the development of the Quantum Drive less than a hundred years before the Sun is set to become a nova. This scientific break-through allows the construction of a fleet of manned interstellar vehicles, including the Starship "Magellan". The "Magellan" escapes the Earth three years before the Sun explodes, an event that is witnessed by the "Magellan"'s crew. In the intervening years the colony on Thalassa loses contact