>If it happens this year for "the good stuff" it will occur for only
>about 4 hours on only one day. This is what I refer to as booming.=A0
>Ice will make noise all the time but the booming is a very special
>event and very different from just ice shifting noise.
>
>I have chased it for 4 years now and not a lot of record time to show
>for it. I have about 1/2 hour of good stuff.
>
>My observations are only my observations and not based on anything
>else. I have never seen research done on the booming event.
>
>The event is due to happen shortly:
>Look for the first night at 0F or colder.
>Then hope for a full sun the next AM with rising temps.
>Record from 10 AM to 3 PM during that morning.
>If we get good snow before this event we are sunk and must travel to
>a snow free sight.
>Therefore please let me know if you see this chain of events occuring
>anywhere in MN or WI. I am watching too.
>
>When booming occures it is very loud and you will hear it for 100
>yards off the lake. I find any sized deep water lake will work but I
>shoot for a 1/2 mile round one by personal preference.
>
>How to mic it is personal preference as it is not rough to capture
>these sounds. I recommend that you do not cool then warm the mic a
>lot. It will take it 30 mins going from a warm car to full cold
>conditions to stabilize so you may hear some mic pops as it cools.
>Going from cold to warm can cause condensation problems until back up
>to full temperature. MD works well at very cold temps. If you use
>dat you may want to put it in a cooler with a warming sports pack.
>
>I would be happy to go attempt this with you Curt if you would like.
>
>Rich
Maybe the mini cold stretch here in the upper
midwest is triggering similar thoughts. I was
just thinking this morning at the bus stop that
ice booms might make a good sound class
expedition this winter. The conditions you
describe Rich are very consistent with the day I
encountered them. Larger, deep lake, clear day,
clear ice, steady radiation and by early
afternoon some surface cracks forming. Separate
from these surface cracks were spatially
dispersed, harmonic "pings" that ricocheted and
tended to cluster around intervals about 5-20
minutes apart. My wild guess is the unusual
sonic qualities come from floating surface layer
of ice reacting very much like a speaker membrane
or drumhead to concussions either from direct ice
strikes or fairly large fractures in deeper
layers of ice. I had a hard time getting a good
event free of snowmobiles and car traffic. If go
again, I'll run the recorder continuously when
conditions are ripe. Heard from a position in the
middle of the lake, its a curiously close, yet
wide event so a wider mic spread might work well.
If the location is remote and background sounds
are low, mics nearer local reflectors like a
hillside of bank of trees might portray more
depth. The events I heard were loud enough to
echo. I'm in if we could meet within 3 hours
Milwaukee. Rob D.
=3D =3D =3D=3D
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