Trace gas Trace gas The most abundant gases in the atmosphere are nitrogen (78.1%), oxygen (20.9%), and argon (0.934%). Combined, oxygen, argon, and nitrogen make up 99.934% of the gases in the atmosphere (not including water vapor). The other gases that are not part of the 99.934% of the atmosphere are called trace gases. The abundance of a trace gas can range from a few parts per trillion (ppt) by volume to several hundred parts per million by volume (ppmv). When a trace gas is added into the atmosphere, that process is called a "source". There are two possible types of sources
Extraterrestrial atmosphere also been observed in the atmosphere of HD 189733 b, another hot gas giant planet. In October 2013, the detection of clouds in the atmosphere of Kepler-7b was announced, and, in December 2013, also in the atmospheres of Gliese 436 b and Gliese 1214 b. In April 2017, an atmosphere was confirmed around Gliese 1132 b. It is the most Earth-like exoplanet to date that is known to have an atmosphere. In May 2017, glints of light from Earth, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in