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One classical thermal escape mechanism is Jeans escape, [1] named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. [2] In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy.
If there is a strong thermally driven atmospheric escape of light atoms, heavier atoms can achieve the escape velocity through viscous drag by those escaping lighter atoms. [2] This is another way of thermal escape, called hydrodynamic escape. The heaviest species of atom that can be removed in this manner is called the cross-over mass. [3]
A University of Colorado, Boulder team has discovered that Mars has an atmospheric "escape route" which may have helped hydrogen drift into space at much faster rates.
This type of atmosphere loss may be common to all planets orbiting Sun-like stars closer than around 0.1 AU. [54] In addition to hydrogen, carbon, and oxygen, HD 209458 b is thought to have water vapor in its atmosphere. [55] [56] [57] Sodium and water vapour has also been observed in the atmosphere of HD 189733 b, [58] [59] another hot gas ...
In most situations it is impractical to achieve escape velocity almost instantly, because of the acceleration implied, and also because if there is an atmosphere, the hypersonic speeds involved (on Earth a speed of 11.2 km/s, or 40,320 km/h) would cause most objects to burn up due to aerodynamic heating or be torn apart by atmospheric drag. For ...
Liquid water and ice emit radiation at a higher rate than water vapour (see graph above). Water at the top of the troposphere, particularly in liquid and solid states, cools as it emits net photons to space. Neighboring gas molecules other than water (e.g. nitrogen) are cooled by passing their heat kinetically to the water.
The escape of any atmospheric gas can be diffusion-limited, but only diffusion-limited escape of hydrogen has been observed in our solar system, on Earth, Mars, Venus and Titan. [1] Diffusion-limited hydrogen escape was likely important for the rise of oxygen in Earth's atmosphere ( the Great Oxidation Event ) and can be used to estimate the ...
A substance that has a larger surface area will evaporate faster, as there are more surface molecules per unit of volume that are potentially able to escape. Temperature of the substance the higher the temperature of the substance the greater the kinetic energy of the molecules at its surface and therefore the faster the rate of their evaporation.