Know a thing or two THE SEA
MAKING THIS SALINE ENIGMA SLIGHTLY LESS MYSTERIOUS
Whatever the weather, some sort of centrifugal force propels us to the sea, whether it’s to swim in its waters, surf its churning waves, paddle in the shallows, or simply to stand on a clifftop and stare at the vast ocean and its shifting colours. On a warm summer’s day, there are few better places to be than lying on a beach towel, a book open but probably unread, listening to the waves tumble and the gulls squawk. It is a combination of elements that soothes and restores the senses.
Perhaps it is the enormity of the sea that continues to draw us. Most of the earth’s surface is covered by it, approximately 70%. Even now, only roughly 5% of it has been explored – there are things down there that we will never see or know. Speculation about what lurks beneath has led to many myths and legends springing up. A lone ship adrift on a becalmed ocean or battling mountainous waves is vulnerable to dangers, real and imagined. Sailors and fishermen, only too aware of the unpredictability of the sea, know to treat it with respect and caution, and conjure stories to make sense of it.
Its mutable nature combined with its steadfast majesty has always inspired artists, from sailors scratching scrimshaw on a whale’s tooth to JMW Turner blasting his canvas with wild brushstrokes and wind-battered vessels, or Japanese artist Hokusai immortalising a single, enormous wave. Musicians, too – whether it’s sailors bellowing shanties on board merchant sailing ships or Claude Debussy or Vaughan Williams trying to capture its shifting moods – are constantly drawn to it.
So it is a sobering thought that the once abundant and limitless ocean is under threat from our mistreatment, in the form of rising plastic pollution, over-fishing and deep-sea dredging. Now, more than ever, is the time to treasure, protect and to enjoy it.
TIDES AND WAVES
TIDES The link between tides and the moon feels magical: how can a planetary body so far away affect our oceans? But it does – the ocean is dragged back and forth by the gravitational pull of the moon and the sun during monthly and yearly orbits. Twice a month, during full or new moons when Earth, sun and moon are in alignment, tidal ranges are larger than average.
Tides are actually huge ocean waves which can be hundreds of miles from crest to crest, yet only a few feet high. Unlike normal waves, which are caused by wind blowing over the water’s surfaces, ocean waves are driven by the gravitational attraction towards the moon and the sun. Tides travel across the ocean towards the coastline where they appear as the rise and fall of the sea surface.
WAVES You think you understand waves, then you discover that they aren’t made of water at all but energy passing through the water. As wind blows across the sea, it creates a friction with its surface water and this disturbance makes a wave crest. Energy passes through these waves which transmits it across the ocean. There are three types to look out for:
Spilling waves occur when the beach slope is shallow and the wave crumbles at the crests creating fringes of white water.
Plunging breakers occur when the slope of the beach or reef is steeper. This forms a tube before crashing down. These breakers are the ‘barrels’ that surfers ride inside.
Surging breakers occur when the seabed is steepest. Water sloshes against the steep shore and back down again, like water in a bathtub when you sit down with a thump. Read more about waves and tides in
The Wavewatcher’s Companion by Gavin Pretor-Pinney (Bloomsbury).