Atmosphere of Earth surface. The refractive index of air depends on temperature, giving rise to refraction effects when the temperature gradient is large. An example of such effects is the mirage. "Atmospheric circulation" is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles. The first atmosphere consisted of gases in the solar nebula,
Opus: The Day We Found Earth their planet of origin to live among the stars. By then, Earth has become a mythical planet and the belief in its existence has become a religion called "Earthology". On the other hand, the human gene pool has deteriorated after millennia of genetic engineering, and the only way to revert this damage is to trace back to the oldest sample of genes left on their long forgotten home planet. Project Earth was then founded and a spaceship named OPUS was launched in order to search for Earth and save the failing human race. The story follows a childlike robot Emeth,