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In aviation, however, water vapor emitted in the atmosphere contributes to global warming (to a lesser extent than CO 2). [11] Liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. [12] The density of liquid hydrogen is only 70.85 kg/m 3 (at 20 K), a relative density of just 0.07.
Hydrogen gas is very rare in Earth's atmosphere (around 0.53 ppm on a molar basis [99]) because of its light weight, which enables it to escape the atmosphere more rapidly than heavier gases. However, hydrogen is the third most abundant element on the Earth's surface, [100] mostly in the form of chemical compounds such as hydrocarbons and water ...
Hydrogen, being the lightest existing gas (7% the density of air, 0.08988 g/L at STP), seems to be the most appropriate gas for lifting.It can be easily produced in large quantities, for example with the water-gas shift reaction or electrolysis, but hydrogen has several disadvantages:
The troposphere is denser than all its overlying layers because a larger atmospheric weight sits on top of the troposphere and causes it to be most severely compressed. Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (3.5 mi; 18,000 ft) of the troposphere.
A hycean planet is a hypothetical type of planet with liquid water oceans under a hydrogen atmosphere. [1] The presence of extraterrestrial liquid water makes hycean planets regarded as promising candidates for planetary habitability. [2] [3] [4] They are usually considered to be larger and more massive than Earth. [5]
The atmosphere has a mass of 4.8 × 10 20 kg, about 93 times the mass of the Earth's total atmosphere. [29] The density of the air at the surface is 65 kg/m 3, [29] which is 6.5% that of liquid water on Earth. [30] The pressure found on Venus's surface is high enough that the carbon dioxide is technically no longer a gas, but a supercritical fluid.
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
The density of air or atmospheric density, denoted ρ, [1] is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variations in atmospheric pressure, temperature and humidity.