Atmosphere of Pluto by the spacecraft "New Horizons". The main component of the atmosphere of Pluto is nitrogen. Content of methane, according to measurements by "New Horizons", is 0.25%. For carbon monoxide, the Earth-based estimates are (2010) and (2015). Under influence of high-energy cosmic radiation, these gases react to form more complex compounds (not volatile at Pluto's surface temperatures), including ethane (CH), ethylene (CH), acetylene (CH), heavier hydrocarbons and nitriles and hydrogen cyanide (HCN) (amount of ethylene is about 0.0001%, and amount of acetylene is about 0.0003%). These compounds slowly precipitate on the surface. Probably, they also include tholins, which are responsible for
Atmosphere of Earth pressure or density, the speed of sound in the atmosphere with altitude takes on the form of the complicated temperature profile (see illustration to the right), and does not mirror altitudinal changes in density or pressure. The density of air at sea level is about 1.2 kg/m (1.2 g/L, 0.0012 g/cm). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law). Atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the barometric formula. More sophisticated models