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Thread: Hydrogen as greenhouse gas

  1. #1
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    Hydrogen as greenhouse gas

    "Stevensonian" worlds are supposed to be kept warm by high pressure hydrogen.
    I thought GHGs had to have at least three atoms in their molecules, to "bend" from infrared photons.
    How does hydrogen work in such rogue planet atmospheres?
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  2. #2
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    Quote Originally Posted by Tom Mazanec View Post
    "Stevensonian" worlds are supposed to be kept warm by high pressure hydrogen.
    I thought GHGs had to have at least three atoms in their molecules, to "bend" from infrared photons.
    How does hydrogen work in such rogue planet atmospheres?
    Collisional infrared opacity. Although a single molecule of hydrogen doesn't possess a dipole moment a colliding pair does, and so can couple to IR radiation during the collision. The effect therefore becomes significant only at high pressures, when collisions are frequent.
    Stevenson invokes cold hydrogen atmospheres with pressures of 100 to 10,000 bars in his rogue planets.

    Grant Hutchison

  3. #3
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    So would that work for oxygen or nitrogen, for example?
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  4. #4
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    Quote Originally Posted by Tom Mazanec View Post
    So would that work for oxygen or nitrogen, for example?
    From https://en.wikipedia.org/wiki/Collis...n_and_emission
    A similar picture is to be expected for the CIA spectra of pure hydrogen gas (i.e. without admixed gases) and, in fact for the CIA spectra of many other gases. The main difference, say if nitrogen CIA spectra are considered instead of those of hydrogen gas, would be a much closer spacing, if not a total overlapping, of the diverse CIA bands which appear roughly at the frequencies of the vibrational bands of the N2 molecule.
    Oxygen may have some complicating factors as it is paramagnetic which adds extra degrees of freedom.

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