Atmosphere of Earth the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around . Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. The study of Earth's atmosphere and its processes is called atmospheric science (aerology). Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann. The three major constituents of Earth's atmosphere are nitrogen, oxygen, and argon. Water vapor accounts for roughly 0.25% of the atmosphere by mass. The concentration of water vapor (a greenhouse gas) varies significantly from around
Suicide in the United Kingdom (4 per cent). Hanging is the most common method used by women, closely followed by self poisoning. Inhalation of domestic gas was the most common method of suicide during the mid-twentieth century. It was completely eliminated by the 1990s as a result of the replacement of coal gas containing toxic carbon monoxide by the non-poisonous natural gas. Later, suicide by inhalation of carbon monoxide from car exhausts became common, but has declined since the introduction of catalytic converters. Age-standardised rates generally fell between 1981 and 2007, with rates in subsequent years increasing to reach a peak of 11.1 deaths per