A constant companion throughout our lifetime, the craggy face of the moon looks down on us from afar, setting the backdrop night after night. Yet far from just a night-time muse, the moon plays a pivotal role in the movement of our tides and the world around us.
Revealed in the artistic tangle of seaweed and shells that decorates our beaches after every surge and retreat of the sea, the work of
the moon is constantly at play. Here’s how.
When you head to the coast, you’ll notice that the level of the sea is always changing. This coming and going of the tide is actually all down to the moon – the earth’s only natural satellite. As the moon’s gravity pulls at the earth, it creates a shift in the earth’s mass, causing it to stretch and bulge. This then has a huge impact on the behaviour of the earth’s water – an element which is far easier to manipulate than solid land.
To Bulge or Not to Bulge
While the entire planet is affected by the moon’s gravitational pull, the areas that are most affected are the points closest to and farthest away from the moon. As all of this water is manipulated and pushed around by the moon’s gravitational pull, it creates two bulges on opposite sides of the world – almost like the earth is being squeezed into a rugby ball-type shape. Whilst we don’t feel any of this ourselves, its impact is very visible on our beaches.
Tide Waits for No Man
How tides work basically relates to how close we are to the earth’s bulges as the earth rotates. When we’re close to the bulges, the force of gravity causes all the water to surge and rush inland. These are earth’s high tides. When we’ve rotated past the bulges and the pull of gravity has eased, this then causes the water to get sucked back out and retreat seaward again. These are Earth’s low tides. In Cornwall, there are two high tides and two low tides every day.
Factoring It In
One high tide to high tide cycle (or low tide to low tide cycle) takes around 12 hours, though the exact point of high tide and low tide changes every day. This is why no Cornish beach EVER looks the same. While the primary factor is the moon, individual tides can also be affected by all sorts of things, like the weather and the shape and size of the beach, as well as surrounding land and ocean depth. Some places in the Med barely have one high tide a day for example, while Southampton experiences the unusual phenomenon of having a double high tide.
Big Hard Sun – Neaps and Springs
Not to be left out, the sun also has a part to play in the earth’s tides. Twice a month, when the earth, sun and moon all line up, the combination of their gravitational power creates extremely high and low tides. These are called spring tides. Around one week later, when the earth, sun and moon create a right angle, the sun’s gravitational power works against that of the moon and the tides become much lower than usual. These are known as neap tides. Our fishermen watch these tides very closely, so they don’t get caught high and dry.
Reading the Tide by the Moon
You can always tell when a spring tide or neap tide is happening, because spring tides always happen on a full moon and the neap tides on a quarter moon. This means that wherever you are, if you can see the moon, you can have a good idea of how the tides will be behaving. So that you can keep up-
to-date with the tides and impress your friends and family with your nautical knowledge, with every online order we will send out a card which shows which stage the moon was at the time of dispatch.
No matter where you are, if you see the moon, you can feel connected to the sea. Remember to always check tide times before heading to your local beach so you can stay beach-safe and savvy.