With the recent rash of hurricanes, I wondered aboput some fundamentals. I
will list some question. I wish to get pointed in the right direction to
understand some of the fundamental physics.

1. How closely related are wind speeds to differences in barometric
pressure? Can one assume that pressure in a storm is reduced by rho*v^2/2?

2. Does the basic storm surge come from the lifting of water by the
reduction in pressure multiplied by some amplifying factor?

3. Is that amplification mainly from slosh or resonanced? Is it mainly from
change in channel size? My background makes me want to think in terms of
nonuniform or tapered electrical transmission lines.

Bill

In article ,
Repeating Rifle wrote:

2. Does the basic storm surge come from the lifting of water by the
reduction in pressure multiplied by some amplifying factor?

This is the inverse barometer effect, for which there is
no amplifier. Given the density of water, it is a small term.
(100 mb pressure deficit gives 1 meter water level change)

3. Is that amplification mainly from slosh or resonanced? Is it mainly from
change in channel size? My background makes me want to think in terms of
nonuniform or tapered electrical transmission lines.

Shoving water towards a shallowing area is the main term, slosh.
The time scales are wrong for resonance -- wind waves have a period
of something like 10 seconds, which is too fast for the storm time scale
of hours, and gravity waves have length scales much larger than the
storm, so it's inefficient at exciting those.

One of the models the NOS (National Ocean Service, part of NOAA)
used to model storm surge is called SLOSH.


--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences

As I said, my background is electrical rather than meterological.

in article , Robert Grumbine at
wrote on 10/3/04 9:27 AM:

In article ,
Repeating Rifle wrote:

2. Does the basic storm surge come from the lifting of water by the
reduction in pressure multiplied by some amplifying factor?

This is the inverse barometer effect, for which there is
no amplifier. Given the density of water, it is a small term.
(100 mb pressure deficit gives 1 meter water level change)

That would have been my first guess, but news reports talk about 12 feet
above normal or the like.

3. Is that amplification mainly from slosh or resonanced? Is it mainly from
change in channel size? My background makes me want to think in terms of
nonuniform or tapered electrical transmission lines.

Shoving water towards a shallowing area is the main term, slosh.
The time scales are wrong for resonance -- wind waves have a period
of something like 10 seconds, which is too fast for the storm time scale
of hours, and gravity waves have length scales much larger than the
storm, so it's inefficient at exciting those.

In electrical terms, the effect of shallowing would be called an impedance
transformation on a tapered transmission line. I believe that is the major
effect that maintains a bore.

There is also something called resonant charging in which a capacitor can be
charged to double the voltage of a battery because the moving charge.
Several stages may generate very high voltages albeit with less charge. I
think slosh would be closely related.

I also have noticed that dumping water into a conainer sometimes causes
small droplets to reach considerably greater heights than th height of the
water source.

One of the models the NOS (National Ocean Service, part of NOAA)
used to model storm surge is called SLOSH.

I saw that, but SLOSH makes for a good acronym.


Thanks for the response.

Bill