Light, the solar workhorse, transmits energy from the sun
that makes things happen on earth. Light makes waves, a result of wind passing
over water surfaces. The wind is solar powered.
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Breaking swells,
Halibut Point |
As long as the sun shines and the earth turns there will be
wind, globally speaking, because air temperatures vary from day to night and our
atmosphere warms/cools at different latitudes, elevations and planetary
surfaces. These variations lead to imbalances in atmospheric pressure. The air
moves responsively to equalize the pressure, creating wind. The friction of air
movement over water, whether puddles or oceans, causes ripples that can be
amplified into waves.
|
Great Black-backed
Gull and Great Cormorant |
Water responds to the energy imparted to it. It becomes a
fluid energy vehicle, an energy transportation system. Wind waves are a
prominent part of that system. When the waves encounter land their energy
transforms the water dramatically into surf.
|
Herring Gull |
The sudden reconfiguration of waves into surf creates
challenges, opportunities, and entertainment for coastal dwellers. The forces
involved can be tremendous and relentless. Adaptive strategies are usually more
effective than resistance.
|
Common Eiders feeding
within the surf zone |
The flow of air causes disturbances to the water surface
that may initially appear random. Steady winds blowing over a long enough
distance will merge the waves and cause crests to form into what is called a
sea, aligned rhythmically in the direction of the wind. Stormy conditions can
make the pattern locally chaotic.
The wind energy imparted to waves results in an orbital
motion to a column of water. The height of the water column is equal to half
the length of the wave, that is, half the distance between wave crests. The waves
carry that energy toward the horizon but the water itself scarcely moves
forward, revolving essentially in one place while the energy passes on, often
very long distances.
|
Swells breaking after
traversing an untroubled sea |
The waves resulting from distant storms may become organized
into swells through assimilation as faster waves overtake slower ones and
larger waves superimpose themselves on smaller ones. Such wave trains can travel
thousands of miles before they reach shore. In the open ocean they lie low and
wide without creating much resistance or disruption. Nevertheless they are
powerfully endowed with energy.
|
Swells rolling in on
Halibut point |
Swells begin to rise when the bottom of their water column encounters
solid land. Even if their direction of travel is almost parallel to the shore rather
than towards it, they pivot shoreward when the drag on their shoreward end
effects a rotation on heading of the rest of the wave. As it approaches shallower
water the wave is forced vertically upward. The bottom of the water column
slows down as it drags over the submerged obstacle. Its upper portion surges
forward until it peaks and collapses. A fortuitous breeze blowing out from the
land into the face of a breaking wave may sustain it somewhat in what surfers
call a "pause-hold" effect. This offshore wind puts a rooster tail of
spray aloft as a complementary flourish to the crashing froth.
|
February dawn |
The
best time to appreciate the effect of wind and waves is to be standing on firm
dry land when a storm passes far out to sea.