The physics of surface waves on water are very interesting, and the maths is
elegant! One outcome is that the longest waves travel fastest - try dropping
a stone in a still pond and see which waves reach the bank first. The
longest waves are also the most energetic, so travel further - when Krakatoa
exploded, the Navy at Plymouth knew something had happened, and roughly
where, from the wave recorded on the tide gauges. The tide in the oceans is
a wave driven by the relative movement of moon and earth, and the speed of a
water wave with a wavelength of half the circumference of the earth is close
to one circumference per 24 hours, which is why there is reinforcement
resulting in the tide having an amplitude much greater than the direct
gravitational attraction implies.

Wind-driven waves are a turbulence phenomenon. There is a cascade of energy
from short to long wavelengths, but as the shear increases, there is a
critical point at which increases in amplitude of the medium-length waves
decrease the transfer of energy from the air to the water. Hence the
flattening of the medium length wind-driven waves.

Not sure about the strom surge being the most destructive aspect of a
cyclone, it will depend on local factors. In Bagladesh, where much of the
country is close to sea leve, then any severe wave will cause severe
problems, whether it is storm related or driven by earthquake etc. However,
in places where the land is higher, than the wave, it does not matter. The
more destructive feature of a cyclone will be the heavy prolonged rainfall,
which results in land-slips, floods etc. This was the problem with Mitch.

Steve Palmer

> -----Original Message-----
> From:	Ilan Kelman [SMTP:[log in to unmask]]
> Sent:	Tuesday, September 19, 2000 2:33 PM
> To:	[log in to unmask]
> Subject:	Isaac's Storm
> 
> I recently read "Isaac's Storm" by Erik Larson (1999, Fourth Estate,
> London) 
> which describes the destruction of Galveston, Texas in 1900 by a
> hurricane.  
> The author describes storm surge as the most destructive aspect of a 
> hurricane and also details the effects of wind, waves, and debris in
> causing 
> casualties and damaging buildings.
> 
> He also includes the following phrases in describing people's observations
> 
> at the height of the storm when most of the city was under water and the 
> wind was at its strongest:
> "He saw no waves, however.  The sea was strangely flat, its surface
> blown smooth by the wind...The fact he saw no waves was ominous,
> although he did not know it." (pp. 210-211)
> "The wind grew so strong it planed the sea.  'The surface of the water
> was almost flat.  The wind beat it down so that there was not even a
> suspicion of a wave'". (p. 226)
> 
> I would be curious to know more about this phenomenon, how the transition
> to 
> smoothness from wave height increasing with wind speed and fetch occurs,
> and 
> why it would be "ominous".
> 
> As well, for those who have read the book--and perhaps lived through a 
> hurricane--how accurate is Larson's account?
> 
> For example, Larson writes "[Hurricane] Camille's rain fell with such 
> ferocity it was said to have filled the overhead nostrils of birds and 
> drowned them from the trees" (p. 98) but qualifies this statement in an 
> endnote that a hurricane researcher "called this an urban legend".  Larson
> 
> also references a 1942 source to propose that the storm surge from a
> typhoon 
> catalysed the September 1, 1923 earthquake in Japan: "low pressure and
> high 
> water, acting in concert, might have caused the earthquake...The sudden 
> differential...might have been enough to fracture a fault line already 
> stressed to its limits" (pp.135-136).
> 
> Would anyone be able to comment further about, or have more information
> on, 
> these statements?
> 
> Thank you for your time and assistance,
> Ilan
> _________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
> 
> Share information about yourself, create your own public profile at 
> http://profiles.msn.com.
> 


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%