Assertion: water vapor | /r/ObjectUse | used as lifting gas
Facets:
value: by a thermal airship
type: OTHER
Source sentences:
text: When water vapor is used as a lifting gas by a thermal airship the water vapor is heated to form steam so that its vapor pressure is greater than the surrounding air pressure in order to maintain the shape of a theoretical "steam balloon", which yields approximately 60% the lift of helium and twice that of hot air.