Noble gas After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons. "Noble gas" is translated from the German noun , first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity. The name makes an analogy to the term "noble metals", which also have low reactivity. The noble gases have also been referred to as "inert gases", but this label is deprecated as many noble gas compounds are now known. "Rare gases" is another term that was used, but this is also inaccurate because argon forms a
Global Atmosphere Watch warning system for chemical or physical changes in the Earth's atmosphere which could be cause for environmental concern. Such changes might involve a change in ozone, and therefore ultraviolet, levels, levels of greenhouse gases, or precipitation chemistry, the culprit in the world's acid rain woes. The GAW consists of a coordinated system of various components, prominent among which are: More than 65 countries currently host and operate the GAW's global or regional measurement stations. There are also "contributing stations" that furnish additional data. Lately, satellite programmes have also become important to the GAW, providing atmospheric data that complement ground measurements.