A High Pressure Atmosphere is a type of atmosphere known for possessing dense gas-filled atmospheres.
- While the definitions of a high pressure and a dense atmosphere overlap, there can be considerable differences as well.
High Pressure Atmospheres are classified as possessing 2.5 standard atmospheres or more of pressure.
History & Background (Dossier)
Worlds with high pressure atmospheres are likely to be teeming with flying creatures, and while most will be equipped with wings, others might be gas balloons, or may be gliders, or 'kites'. An aerial ecology really thrives when a very small planet (with low gravity) has a dense atmosphere.
- Dense atmospheres also retain a lot of heat resulting in a great deal of highly energetic weather; imagine gargantuan, continent-spanning hurricanes, powerful electrical storms, supersonic winds and football-sized hailstones! Take a weather phenomenon and max it out! 
- And yet while very impressive, these densely atmosphered worlds don’t come even close weather-wise to the unimaginably energetic and destructive storms of a Storm World.
References & Contributors (Sources)
- Marc Miller. Worlds and Adventures (Game Designers Workshop, 1977), 5.Marc Miller, Robert Eaglestone, Don McKinney. Worlds and Adventures (Far Future Enterprises, 2019), 5.
- J. Andrew Keith. Exotic Atmospheres (Game Designers Workshop, 1983), 1-16. (Special Supplement 2 from the periodical Journal of the Travellers' Aid Society 17)
- Marc Miller. Referee's Manual (Game Designers Workshop, 1987), 22.
- Joe Fugate, J. Andrew Keith, Gary L. Thomas. World Builder's Handbook (Digest Group Publications, 1989), 64-68.
- Terrance McInnes, Dave Nilsen. World Tamer's Handbook (Game Designers Workshop, 1994), 11-17.
- Jon F. Zeigler. First In (Steve Jackson Games, 1999), 70,72.
- Paul Drye, Loren Wiseman, Jon F. Zeigler. Interstellar Wars (Steve Jackson Games, 2006), 125-6.
- Gareth Hanrahan. Mongoose Traveller Main Rulebook (Mongoose Publishing, 2008), TBD.
- Marc Miller. T5 Core Rules (Far Future Enterprises, 2013), 409.
- Paul Elliott. The Universal World Profile (Zozer Games, 2016), TBD.
- Traveller Wiki Editorial Team
- Author & Contributor: Lord (Marquis) and Master of Sophontology Maksim-Smelchak of the Ministry of Science