Translations:Atmosphere/2/en

Description (Specifications)

Atmospheres have a mix of different gases, some in great amounts, while others are barely detectable. Atmospheric mixes include active and inert gases. On Earth, oxygen (02) is active, but forms less than 25% of the total atmosphere. Three times as much is nitrogen (N2), plus a few trace elements such as argon. These inert gases are not usually required by animal or plant life, and take no part in the chemical reactions essential for life (except for nitrogen, a special case). They are, nonetheless, part of the atmosphere. In this AAB article, when we refer to a specific gas such as methane making up an atmosphere, we are referring to the active element, which may make up only a fraction of the total atmospheric mix.

World Atmosphere Classification Codes Table

As a generality, small worlds have insufficient gravity to maintain an atmosphere and tend to have thin or trace atmospheres while larger worlds grow increasingly dense. Corrosive and insidious worlds tend to be at extreme ends of the tolerable temperature spectrum.

Atmospheric Code Descriptions
Symbol	Code	Specific Description	General Description	Pressure (Atm)	Remarks
	0	Vacuum	Vacuum	< 0.001	Vacuum requires a vacc suit. The atmosphere has a pressure of less than 0.001 atmospheres, which requires the use of a vacc suit.
	1	Trace	Vacuum	0.001-0.09	The atmosphere has a pressure of less than 0.1 atmospheres, which requires the use of a vacc suit.
	2	Very Thin / Tainted	Vacuum	0.10-0.42	Very Thin tainted requires a filter respirator combination
	3	Very Thin	Vacuum	0.10-0.42	Very Thin requires a respirator. The atmosphere has a pressure of 0.1 to 0.42 atmospheres, which requires the use of a respirator to ensure sufficient oxygen.
	4	Thin / Tainted	Thin	0.43-0.70	Tainted requires a filter mask. The atmosphere contains an unusual taint such as such as disease, a hazardous gas mix, pollutants, or sulfur compounds which requires the use of a filter mask.
	5	Thin	Thin	0.43-0.70	Shirtsleeve World: No survival gear required. The atmosphere has a pressure of 0 43 to 0.70 atmospheres. The atmosphere is a standard oxygen/nitrogen mix, which is breathable without assistance.
	6	Standard	Standard	0.71-1.49	Shirtsleeve World: No survival gear required. The atmosphere has a pressure of 0.71 to 1.49 atmospheres. The atmosphere is a standard oxygen/nitrogen mix, which is breathable without assistance.
	7	Standard / Tainted	Standard	0.71-1.49	Tainted requires a filter mask.
	8	Dense	Dense	1.50-2.49	Shirtsleeve World: No survival gear required. The atmosphere has a pressure of 1.50 to 2.49 atmospheres The atmosphere is a standard oxygen/nitrogen mix, which is breathable without assistance.
	9	Dense / Tainted	Dense	1.50-2.49	Tainted requires a filter mask.
	A (10)	Exotic	Exotic , Conventional	varies	An unusual gas mix which requires the use of oxygen tanks, but protective suits are not needed.
	B (11)	Corrosive	Exotic , Conventional	varies	A concentrated gas mix or unusual temperature creates a corrosive environment, which requires the use of a Hostile environment suit or vacc suit.
	C (12)	Insidious	Exotic, Conventional	varies	The atmosphere is similar to a corrosive atmosphere, but extreme conditions cause the corrosive effects to defeat any protective measures in 2 to 12 hours.
	D (13)	Dense, high	Exotic, Unusual	2.5 or greater	Typically no survival gear required under many conditions. Pressure at or below sea level is too great to support life but is breathable at higher altitudes.
	E (14) †	Ellipsoid †	Exotic, Unusual	0.5 or less	Typically no survival gear required under many conditions. The world’s surface is ellipsoidal, not spherical. Because the atmosphere remains spherical, surface atmospheric pressure ranges from very high at the middle to very low at the ends. Breathable bands may exist at some point within the range of pressure.
	F (15) †	Thin, low †	Exotic, Unusual	varies	Typically no survival gear required under some conditions. This world is large and massive, with a thin atmosphere which settles to the lowest levels of the terrain. The atmosphere is un-breathable at most altitudes except the very low ones (…as in depressions or deep valleys).

^† - NOTE: In MgT and T5, Atm type E is "Thin, Low", and Atm type F is "Unusual", which includes (but is not limited to) Ellipsoidal atmospheres.