>I must have skipped the class on Mars atmosphere. // Don't worry, me too ...
>Will some one tell me the composition?
This was easy to find at http://seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html
Carbon Dioxide (C02) ...95.32% / Nitrogen (N2) ...2.7% / Argon (Ar) ...1.6%
Oxygen (O2) ...0.13% / Carbon Monoxide (CO) ...0.07% / Water (H2O) ..0.03%
Neon (Ne) ...0.00025% / Krypton (Kr) ...0.00003% / Xenon (Xe) ...0.000008%
Ozone (O3) ...0.000003% . So it's mainly CO2.
The Atmospheric pressures is seasonally changing from 7.3 and 10.8 millibars
(landing site Viking 2). That's about 1% of the air pressure at Earth at sea-level.
At top of Olympus Mons (Alt. 27 km) atmospheric pressure is about 1 millibars.
>Is it capable of conducting sound waves? If so, at what frequencies?
I had to stick on it to find the appropriate altitude at Earth, where the atmospheric
pressure is about 10 millibars and I've come up with that:
Atmosphere pressure at Earth falls to a tenth about each 17 km, reaching 100 millibar
at the tropo-pause, 10 millibar at an altitude of 34 km, which is right in the middle of
the stratosphere, 1 millibar at 50 km, which at the strato-pause and 0,001 millibar at
an altitude of 100 km, last one mentioned explicitly by the used encyclopedia.
Temperature at an altitude of 35 km is about minus 50 degree Celsius.
Temperature at Mars varies from minus 120 degrees to plus 20 degrees Celsius.
In the upper stratosphere (alt. 35-50 km) temperature moves up to plus 0 degrees
Celsius because of O3 absorption and, now please listen, this atmospheric belt is
reflecting sound waves coming from Earth surface back to Earth surface again.
That means, at the same pressure and the same range of temperature as up at Mars,
sound waves are moving. Sonic speed is less than at Earth sea-level as it declines by:
...................v = Square-Rood (temperature * pressure / specific gravity)...................
About frequency, I have to assume. I think, CO2 is of higher specific gravity than
our atmospheric N2/O2 mix. Under same atmospheric pressure a human voice is of
higher frequency, when breathing Helium. So same voice should be of a lower
frequency, when breathing nearly pure CO2. But wait a minute, pressure is another
factor for frequency. A violin increases its frequency as atmosphere pressure drops,
as the energy of her frequency can push easier the molecules of the thinner medium.
So, I'm not quite sure about that, but I would say frequency moves up. Oh, let's say
I'm sure. Talking breathing in gives you an higher voice, than talking breathing out.
About loudness I would suppose, same energy emitted same energy received. But
thinking of a motorboat, it is heard better under water than above; and air is a good
isolator of sound too. Therefore, I would say, the intensity of sound is decreasing
faster at Mars than at Earth referring to the distance to the sound emitting center.
Okay these are my thesis. Anyone else ??
m.f.g.
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