Answer to Question 1Many factors contribute to the severity of a storm surge. The most important factor is the
strength of the storm generating the surge. The low atmospheric pressure associated with a great storm will draw the ocean surface into a broad dome as much as 1 meter higher than
average sea level. This dome of water accompanies the storm to shore, becoming much
higher as the water gets shallower at the coast. There the water ramps ashore, driven forward
by large storm-generated wind waves. A storm surge is a short-lived phenomenon.
Technically it is not a progressive wave because it is only a crest; wave- length and period
cannot be assigned to it. Water in a storm surge does not come ashore as a single breaking
wave but rushes inland in what looks like a sudden, very high, wind-blown tide. Indeed,
storm surges are sometimes called storm tides because the volume of water they force
onshore is greatly increased if the surge arrives at the same time as a high tide. The wrong
combination of low atmospheric pressure, strong onshore winds, high tide, and bottom
contour can be especially dangerous if estuaries in the area have been swollen by heavy
rainfall preceding the storm.Storm surges have had catastrophic consequences.
Answer to Question 2Large waves (i.e., seiche waves, tsunami waves, tides) have typical wavelengths of > 200 km
(125 mi). To be classified a deep-water wave, a wave must be moving through water deeper
than half their wavelength. Half the wavelength of large waves is upwards of 100 km (62 mi).
No ocean is that deep. Therefore, seiches, seismic sea waves, and tides are forever in water
that to them is shallow or transitional in depth.