Szczepan Bialek wrote:


"The Earth is constantly immersed in the solar wind, a rarefied flow of hot
plasma (gas of free electrons and positive ions) emitted by the Sun in all
directions, a result of the two-million-degree heat of the Sun's outermost
layer, the corona. The solar wind usually reaches Earth with a velocity
around 400 km/s, density around 5 ions/cm3 and magnetic field intensity
around 2-5 nT (nanoteslas; Earth's surface field is typically 30,000-50,000
nT). These are typical values. During magnetic storms, in particular, flows
can be several times faster; the interplanetary magnetic field (IMF) may
also be much stronger."


Sure... the number density of ionized particles is somewhat bigger than
the 5/cc you describe above, so solar wind is actually not a big
contributor to it. Most of the ionization comes from UV ionizing the
air atoms/molecules. (that's what the whole daytime sky wave off the F
layer is all about, after all.. working Australia from the California on
20 meters at 5AM CA time probably isn't a good bet)



The aurora is NOT caused by acoustic waves.

" In the explosive event that a coronal mass ejection (CME) is reported it's
time to hop into action because this super-charged solar wind is traveling
fast (maybe 3-to-5 million miles per hour). When this energy sweeps by the
earth 1-to-3 nights later there is a very good chance of aurora activity".
From: http://aurorahunter.com/aurora-prediction.php


That's not acoustic. That's just particles streaming out into space,
and because there's not many other particles to bump into, most of them
get to Earth