How a Foreshortened Arctic Led Norse Seamen to New World
by:   Waldemar Lehn, H. Leonard Sawatzky, and Irmgard Schroeder
in:   "Science Digest" (April 1980)
 
      Were the Norse discoveries of Iceland, Greenland, and the
New World "accidental"?  This has been the accepted theory among
historians, but the fact may simply be:  Those early voyagers saw
the new land they were heading for before they set sail, even
though the land was far beyond the horizon.
      The key to this seeming paradox lies in an understanding of
meteorological optics (transmission of visual images through the
atmosphere) and, in particular, an anomaly known as the arctic
mirage.  The "arctic mirage" is as typical of high-latitude
regions as the "desert mirage" is of desert areas; in Greenland,
it occurs on as many as 20 days out of 30 during some months.
      The mirages occur when the air immediately above the Earth's
surface is colder than the air at the higher elevations.  Such an
increase of temperature with elevation is known as a temperature
inversion.  Under such conditions, light rays do not travel in
straight lines, but are bent (refracted) around the curvature of
the Earth.  The stronger the temperature inversion, the greater
the curvature of the light rays.  When ray curvature equals Earth
curvature, it creates the optical illusion that the earth is
flat.  In more extreme cases of temperature inversion, which are
by no means uncommon, the Earth's surface appears saucer-shaped,
and objects which are normally out of sight--coastlines, for
example--are raised into view.  The early Norsemen called this
type of arctic mirage hillingar, a term still used in Iceland.
      Rural folk of the regions rimming the North and Baltic Seas
and the North Atlantic have a tradition of knowledge of the
arctic mirage that goes back as far as history and folklore
serve.  People used to live much closer to nature than we do. 
Their survival depended on a keen sense of observation and the
ability to use that which nature provided.  Since the arctic
mirage was part of their natural environment, it must have
affected their lives.
      The Norse, like the Celts, Greeks, and Romans, believed in a
flat or saucer-shaped world.  These beliefs were remarkably
similar throughout the known world, and remained essentially
unchanged until the 15th century.  It was generally believed that
the world was an island surrounded by oceans, beyond which was
the Abyss.  The distant, rather dim region near the edge of this
world became known as Thule.
      Since all streams flowed to the ocean, it was reasoned that
all waters must return to the land by subterranean channels,
their submarine entrances marked by deadly whirlpools--Scylla and
Charybdis, for example.  Based on Fridtjof Nansen's postulation,
it has generally been assumed that these concepts were trans-
ferred from the Mediterranean basin to northwestern Europe by
osmosis of folk legend from people to people.
      We consider it extremely unlikely, however, that nonliterate
peoples would absorb such concepts into their folklore had they
not been corroborated by their own observation and experience. 
The limits of the world known to early North Atlantic peoples
were, in fact, as their legends described them.  Whenever the air
was clear enough to see over long distances, the arctic mirage
was likely to cause the surface of the world to extend outward
towards its "edge" at dead level or at a slight incline.
      Since Mediterranean travelers were voyaging to "Britain,
Thule, and the land from which amber comes" at least as early as
the 4th century B.C., they may well have returned with observa-
tions and concepts which then entered the written lore of their
civilization.  Indeed, it seems possible that such observations
had much to do with the failure of the spherical earth theory to
win acceptance for many centuries.
      The hillingar effect, which produces the saucer-shaped world
with very distant objects raised into view, has a natural
appearance.  Yet it conveys a great deal of information to the
observer about objects ordinarily below the horizon.  The land-
scape appears so natural that, unless one is familiar with the
view under normal conditions, the observer does not doubt the
evidence perceived by the senses.
      Hillingar can visually bridge very large distances, some-
times hundreds of kilometers.  Such distances typify the separa-
tions between the successive settlements that gradually spanned
the North Atlantic from Europe to America.  For example, accurate
maps of the polar regions show that the maximum separation in
this chain of islands is the 385-kilometer gap between the
Faeroes and Iceland.
      A legend in the Faeroe Islands describes an arctic mirage
and suggests its significance in the lives of the early settlers. 
The legend tells how land would, from time to time, rise from the
sea at a great distance, but that it would disappear again unless
men went out and laid iron upon it.  The inverted logic, so
typical of legends, is both amusing and informative.  The
tantalizing appearance and disappearance of islands, with which
the inhabitants would have become increasingly familiar through
the years, would certainly have been a tempting goal to these
restless, seafaring folk.
      The Norse concept of the world included dangerous phenomena
that existed at the edges of their world.  Their sagas tell of
the dreaded hafgerdingar (sea fences) which were capable of
capturing ships and sending them down to certain destruction. 
Medieval mariners reported that the waters between Europe and
Greenland were filled with treacherous whirlpools, vortices, or
sea fences.
      Various explanations are advanced for this preoccupation
with the much-feared hafgerdingar.  Peter Frederik Suhm's sugges-
tion in 1790--that the legends were based on a powerful eddy, or
Maelstrom, near the Lofoten Islands--is no more satisfactory than
Scylla and Charybdis.  The Lofoten Islands lay on no shipping
lane and, therefore, came under the purview of few, if any,
mariners.
      Theories about the hafgerdingar based on possible encounters
with submarine earthquakes do not yield a satisfactory explana-
tion either.  Typical of such events is the fact that, except in
the immediate vicinity, the disturbance of the sea surface is
minimal.  The odds against ships being over the epicenter of an
earthquake with sufficient frequency for the experience to become
the basis of a firmly established legend are too great to be
taken seriously.
      Nor can the legendary hafgerdingar be written off as pure
myth.  The 13th-century King's Mirror speaks of hafgerdingar, but
also presents sober, amazingly accurate accounts of the large
marine mammals found in the North Atlantic, and the nature of the
sea ice and its drift.  It would appear irresponsible to accept
that part which conforms to out own knowledge, and dismiss the
rest as the product of fear-ridden imagination.  There must be an
element of truth to these legends.
      The hafgerdingar did exist, and still do--albeit only as
optical illusions.  Like the hillingar, they are an arctic mirage
caused by temperature inversion and increased atmospheric refrac-
tion.  To an observer, the appearance of the foreground remains
normal, but the horizon becomes elevated, and "walls" or
"barriers" appear in the distance.  It is simply an exaggerated
case of the saucer-shaped Earth:  The apparent upward slope of
the sea near the horizon is foreshortened, and the actual horizon
appears as a wall only a few kilometers distant.
      At sea, in the absence of normal terrestrial aids to orien-
tation, the visual impact of the hafgerdingar must have been
frightening indeed.  The mariner would have received an almost
overwhelming impression of being below the lip of a wide vortex,
the waters poised as if ready to engulf him.  The presence of
another vessel within the field of view would only strengthen the
impression:  Even at distances of only a few kilometers, the
waters beyond would loom much higher than the neighboring vessel. 
In medieval times, the high losses among trading ships in the
North Atlantic could easily have kept alive the belief that such
a vortex had drawn the ships down to destruction.
      The clues found in early legends definitely establish a
general, if at times misunderstood, awareness of the arctic
mirage.  Proof of these theories, however, must lie in modern,
well-documented sightings, and in the development of meteoro-
logical optics on a sound scientific basis.
      Even though the shortest distance between Greenland and
northwest Iceland is 300 kilometers, scientists have documented
that ". . . you cannot go far offshore from northwestern Iceland
without being able to see both countries . . . You cannot climb
the mountains of northwestern Iceland on many different days
without catching a glimpse of the [Greenland] coast.  The moun-
tains . . . are of such height that the tops are inter-visible
whenever the skies are clear."
      Obviously, under normal atmospheric conditions, the mountain
tops would not be inter-visible, even with clear skies:  the
earth's curvature interposes a gap of some 60 kilometers in the
line of sight.
      Viewed with a basic understanding of the arctic mirage in
its many forms, certain aspects of the old legends take on
completely new significance.  The new interpretation seems to be
both more logical and more plausible than previously held
theories.
                                                           LEHN-01.ART