NATURAL PHENOMENA 



The Flaming Aurora comprise a quick moving form of waves of 

 luminosity moving toward the zenith, or of invisible waves which 

 cause segments of arc, bands, or patches to appear and disappear 

 rhythmically but always vrith an upward motion. One form con- 

 sists of arcs which extend upward out of a quiet arc. Another type 

 occurs when these waves move up ray forms giving the impression 

 of flames. They often appear near the peak of a display, though 

 may be seen several times in one night. 



The Glow form is a faint luminosity, which, when seen near the 

 north horizon, resembles dawn. When appearing high in the sky it 

 resembles a translucent veil. It occurs alone only at the beginning 

 and end of displays. However, after other forms become prominent 

 it is easily overlooked. The activity of an auroral display often ends 

 in a glow which may persist for several hours. 



A Patch or Spot consists of patches or spots of diffuse light with 

 the edges more well defined than the edge of a glow form. The patch 

 or spot is usually whitish but may be a deep red in color. 



BIOLUMINESCENCE 



Bioluminescence, often incorrectly termed phosphorescence, is 

 the production of light by living organisms in the sea. Bioluminescent 

 displays must be triggered by some physical, chemical, or mechanical 

 stimulus. Generally, these displays are stimulated by surface wave 

 action, ship movement, fish and whale movement, subsurface waves, 

 upwelling, eddies, physical changes in sea water, surfs, tide rips, 

 and others. 



In most cases bioluminescence is a reaction between luciferin 

 and oxygen in the presence of luciferase. Luciferin is a heat stable, 

 easily oxidized compound. Luciferase is an enzyme which accelerates 

 the reaction. Bioluminescence may be produced by secretions of 

 specialized glands, or by symbiotic bacteria. 



Sketch of a phosphorescent wheel 



Marine displays are generally grouped in three general categories: 

 (1) sheet-type, often appearing as a sheet-like glow extending for 

 several miles over the sea surface; these are caused by tiny one- 

 celled animals, protozoans; (2) spark-type, observed as innumerable 

 flickering points of light; these are caused by minute shrimplike 

 crustaceans; (3) globe-type, observed as glowing balls of light 

 produced by jellyfish and tunicates when drifted together in groups 

 in the sea. 



Numerous reports concerning these phenomena have been re- 

 ceived from ships throughout the world. Some of the descriptive 

 terms submitted by observers are as follows: "appeared as shoal 

 water, low-lying fog bank, broad belts, narrow belts, ribbons, rivers, 

 milky patches, bars moving at great speed, flashing spots, white 

 water, beams of light, like a search light, patches resembling pack 

 ice, pale blue — horizon to horizon, millions of electric lights, starry 

 sky, round blobs, cloud-like patches, continuously changing form, 

 large anti-clockwise pinwheels," and many others. 



BURNING CLIFFS 



Along the western shore of Franklin Bay, Northwest Territories, 

 Canada, the coast is backed for several miles by a range of steep 

 hills known as "Smoking Hills" or "Burning Cliffs". The cliffs range 

 from about 300 to 500 feet in height and are in places composed of 

 bituminous alum shale. Their name is from the burning mineral 

 deposits which emit clouds of smoke and steam, particularly in 

 spring and summer. 



Some areas of the cliffs burn in places for years. At night the 

 fires are visible a considerable distance to seaward and resemble 

 numerous camp fires. The fires burn out in some places and start up in 

 others. The burned out areas cause the cliffs to be washed and 

 undercut by the sea in places. 



The smoke has a sulphurous odor but the fires are reportedly not 

 of volcanic origin. The water in the streams and ponds along this 

 coast is mostly undrinkable because of the alum content and other 

 mineral salts. 



DESTRUCTIVE WAVES 



Unusual sudden changes in water level can be caused by seismic 

 sea waves or violent storms. These two types of destructive waves 

 have become commonly known as tidal waves, a name which is 

 technically incorrect as they are not the result of tide producing 

 forces. 



Seismic Sea Waves are set up by submarine earthquakes. Many 

 seismic disturbances do not produce sea waves and often those 

 produced are small, but occasional large waves can be very damaging 

 to shore installations and dangerous to ships in harbors. 



These waves travel great distances and can cause tremendous 

 damage on coasts far from their source. In 1946, one originating in 

 the Aleutian Trench caused $25,000,000 damage in the Hawaiian 

 Islands 2,200 miles away. 



The speed of seismic sea waves varies with the depth of water, 

 reaching 300 to 500 knots in deep water of the open ocean. They can- 

 not be detected in the open sea from a ship or from the air because 

 their length is so great, sometimes a hundred miles, as compared to 

 their height, which is usually only a few feet. Only on certain types 

 of shelving coasts do they build up into waves of disastrous 

 proportions. 



There is usually a series of waves with crests 10 to 40 minutes 

 apart, and the highest may occur several hours after the first wave. 

 Sometimes the first noticeable part of the wave is the trough which 

 causes a recession of the water from shore, and persons who have 

 investigated this unusual exposure have been engulfed by the on- 

 coming crest. Such an unexplained withdrawal of the sea should be 

 considered as nature's warning of an approaching wave. 



A warning system has been organized in the Pacific with its 

 center in the Hawaiian Islands. Improvements for rapid determina- 

 tion and reporting of earthquake epicenters are being made, but no 

 method has yet been developed for determining whether destructive 

 waves will be generated. 



Stormwaves.—A considerable rise or fall in the level of the sea 

 may result from strong winds and a sharp change in barometric pres- 

 sure. In cases where the water level is raised, higher waves can form 

 with greater depth and the combination can be destructive to low 

 regions, particularly at high stages of tide. Extreme low levels can re- 

 sult which are considerably less than those shown on nautical charts. 

 This type of wave occurs especially in coastal regions bordering on 

 shallow waters subject to tropical storms. 



Seiche is a stationary vertical wave oscillation with a period 

 varying from a few minutes to an hour or more, but somewhat less 

 than tidal periods. It is usually attributed to external forces such 

 as strong winds, changes in barometric pressure, swells or seismic 

 sea waves disturbing the equilibrium of the water surface. Seiche 

 occurs both in enclosed bodies of water and is superimposed upon 

 the tides of the open ocean. When the external forces cause a short- 

 period horizontal oscillation of the water, it is called Surge. 



The combined effect of seiche and surge sometimes makes it 

 difficult to maintain a ship at its berth alongside a pier even though 

 the water may appear to be undisturbed. On occasion ships have 

 incurred damage or caused damage to pier facilities after mooring 

 lines have been parted repeatedly under such conditions. 



Since prediction of this phenomenon is nearly impossible, mariners 

 should be alert to the ship's behavior at all times especially in strange 



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