4 ms·
>>> yes, intuitively, hot water vapor rises Temperature is just an expression of mean kinetic energy of particles. If gases (especially light gases) are hot en
by tomr_stargazer 12y ago
>>> yes, intuitively, hot water vapor rises
Temperature is just an expression of mean kinetic energy of particles. If gases (especially light gases) are hot enough, their kinetic energy can correspond to a velocity that actually exceeds the escape velocity of Earth's gravitational well. This is how hot gases can be removed completely from the Earth's atmosphere (and then solar wind & radiation take care of removing it from there). Even at today's atmospheric temperatures, helium gas (molecular weight of 4 atomic mass units, much lighter than molecular oxygen, nitrogen, etc.) can escape from Earth's atmosphere.
- jameshart 12y agoRight, that was my thinking; so does the same not apply to nitrogen, and methane (which I think both have lower molecular mass than water)? (EDIT: actually, on second thought, N2 would have a higher molar weight than H2O...)
- tomr_stargazer 12y agoYes on your edit. The origin of Earth's atmospheric nitrogen is thought to be in part due to outgassing (in other words, gas that was stored inside rocks in the early Earth and then released from inside), but is highly uncertain & debated. It's actually so poorly constrained that it may end up being my PhD thesis topic (astrophysics and origins of planetary systems). So not even the experts know, yet, although cometary delivery in cyanide ices from comets is a leading hypothesis (similar to the delivery of water ices).
- efuquen 12y agoWas digging around and found some good info, looks like tomr already answered the Nitrogen part of the question, which is the same info I found. As far as methane, it seems to all mostly be biogenic[1]. [1] - http://www.astrobio.net/news-exclusive/methane-on-earth/ http://www.astrobio.net/news-exclusive/methane-on-earth/