In Minnesota we refer to this as "Booming" It occures best in falling
temps. The ideal time when a lake is the loudest is 1-3 inches and a
rapid temp drop below 0 F at sunset on a cloudless day. On the best
day of the year you can record continous booms.
On most any day below -10 F you will get some booms. My guess on the
wind is just that it aided the temp drop.
Since water expands as temps drop something has to give. Us
fisherman consider a loud lake to be a safe lake because it proves
that the ice is building.
Rich Peet
--- In Dan Dugan <> wrote:
> Dean Grantham <>, thanks for this fascinating
> report that you sent to Questionbird at the Nature Sounds Society.
> I'm posting it on the Nature Recordists mailing list
> <> to see if anybody else has
> experienced this phenomenon.
>
> Do people at the park say this happens regularly, or seasonally?
>
> -Dan Dugan
> Answerbird
>
> *** begin quoted message
>
> Hi--
>
> My wife and I just returned from a trip to the Canadian Rockies
> during which we heard loud, ethereal series of harmonic sounds
> emanating from two lakes over a period of 5 days. The lakes were
both
> in Banff National Park: Lake Louise, near the village of the same
> name, and Upper Vermillion Lake just outside Banff. We believe we
> know the physical source of the sound, but can only guess at the
> dynamics producing them.
>
> We're pretty sure the sound was coming from the (approximately 2-
inch
> thick) ice itself, since we witnessed a very similar sound being
> produced at Lake Louise by thoughtless tourists tossing rocks onto
> the ice--the ice acted like the membrane of a drum, producing the
> eerily beautiful sound. However, during our time there we heard the
> ice produce a very similar sound, much more strongly, and heard
> it racing quickly from one portion of the lake to another, when
there
> was no-one else there, no evidence of scree falling from the
slopes,
> etc. The sounds were pronounced and prolific when the temperature
was
> well below freezing, and absent when the temperature was close to
the
> freezing point. This suggested to us that as ice continued to form
> and expand, the built-up pressure suddenly released through
cracking,
> or portions of ice popping up and over other layers, producing the
> beautiful vibrations.
>
> However, the mechanism at Upper Vermillion Lake must have been
> different--the pond wasn't frozen shore-to-shore as it was at Lake
> Louise. (Strictly speaking, the western end of the long narrow Lake
> Louise was still clear of ice--elsewhere there was 1-3 inches thick
> right to the shore.) At Upper Vermillion Lake, perhaps 30 yards of
> open water remained between the ice sheet and shores at least
> half-way around the lake, though we believe the far end of the
> lake may have been frozen to the shoreline. We spent about an hour
> listening to more subtle, yet clear harmonic tones that also seemed
> to wander across the span of the lake, but the open water here
seemed
> to eliminate the possibility of ice pressure being suddenly
released.
> However, there was a stiff, variable wind coming from the west, and
> we wondered if the ice sheet might be slightly lifted because of
> reduced pressure (the Bernoulli effect) and subsequently released
as
> the wind shifted. Perhaps this induced cracking that could produce
> the beautiful sound? (There was little or no wind at Lake Louise on
> the other hand.)
>
> No-one I spoke to had a ready explanation for the mechanism
producing
> these sounds. The ice on both ponds was completely clear of snow.
In
> both lakes the stereophonic effect produced by the rapid migration
of
> the beautiful sounds from one area of the ice sheet to another was
> dramatic and mesmerizing.
>
> Still, we're unsure the sounds were related to cracks forming, or
> ice-subduction or whatever, because we didn't ever hear any sudden
> "snap" at the onset of the harmonic sounds. Can anyone
> confirm/correct our theories about the formation of these sounds,
and
> has anyone recorded these lovely songs?
>
> Thanks...
>
> Dean Grantham
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