Significant Weather
Significant weather in the weather field is any weather phenomena,
which reduces horizontal visibility to less than 7 miles and "vertical
visibility" less than 1,000 ft.
Fog
The greatest frequency of fog in the vicinity of Denmark occurs from mid
autumn to mid spring. During this period of colder surface temperatures, the
great stabilizing affect of these colder temperatures and the moisture available
from the nearby waters cause fog to be relatively frequent. There is also a
relatively high frequency of occurrence of frontal fog in the vicinity of
Denmark.
- Sea Fog
- is formed when warmer air from the south drifts northward across an
increasingly cooler sea surface. In the summer, sea fog occurs along the
coast of Norway frequently enough to be a problem to maritime and air
traffic. Maximum frequency of fog is in July.
- Frontal Fog
- is formed when relatively warmer air is gently lifted along the gradual
slope of a warm front. This type of fog usually does not usually create
problems for the coastal regions of Scandinavia as it is usually found in
the interior regions. The Vikings were sure to have encountered this type of
fog, but usually on their inland travels. They would not often encounter
this type of fog on their ocean/coastal travels.
- Radiation Fog
- is formed when moist air at the surface weak winds are cooled. The cooling
process can happen at night or when relatively warmer ocean air is brought
over much cooler land. This type of fog usually occurs after the passage of
a frontal system when moist oceanic air is brought to the Scandinavian
Peninsula countries.
- Stratus Clouds
- are a flat type of cloud formed under stable atmospheric conditions. They
typically form above the ground but can be formed on the ground at which
point they are termed "fog" and during the daily heating (the sun
rises and warms the earth) the fog lifts and is termed a stratus
cloud. Higher elevations which are still in the clouds are foggy.
Often when the Vikings were traveling along the coastal shores their foggy
conditions during the night and morning hours would clear out lift by late
morning.
How the Vikings could use fog:
- They could plan an invasion and use the fog as a cloak for a surprise
attack and then retreating in the fog after. By having predestined meeting
places they could meet there after before returning home.
- When traveling from the open ocean, they could wait until fog began to
form prior to gaining entrance to their coastal regions leaving any
followers unsure of where they entered.
- Since fog forms along moist areas, they could look for fog over the hills
to quickly find where streams, rivers and lakes were located.
- When fog begins to form at night there is a good chance that the night may
not be too windy, and that knowledge could be utilized in many ways.
Since their cooking fires were within their homes with open holes in the
roofs, they could cook or cure meats under a heavy fog.