Have you ever wondered how tides work – and why the sea comes in and out? It’s regular and predictable, no matter what else is happening, here on the Fylde Coast or elsewhere in the world.
The water comes in and goes out, twice every day, just like clockwork. As they say ‘Time and tide waits for no man’. Their annual pattern is dictated by the seasons and the moon. But have you ever thought about why they change every day?
How we see the Tide
- There are two high and two low tides in each 24 hour period.
- It moves forward about half an hour with each tide, with one high/low tide every 12 hours and 25 minutes.
When the tide has been out as far as it possibly can, at each following tide the depth of water gets progressively shallower until it reaches its smallest depth. Then it reverts to once again go deeper with each tide until it reaches its deepest. And so on…. That’s why you’ll hear it referred to as a ‘9m or a 7m tide’ etc.
The very highest maximum depth to which the tide comes in and goes out are called ‘Spring tides’. Confusingly, ‘Spring Tides’ (sometimes just called ‘Springs’) happen in both Spring and Autumn.
‘Calder Dale’ is a scientist who follows the Visit Fylde Coast YouTube channel. He gave this explanation of how the depth of a tide is measured: “All tidal heights are taken relative to the mean sea level taken at Newlyn in Cornwall. This was derived early in the 20th century using a tide staff with readings taken over a 6 year period. There is a brass bolt at the Observatory that you can see which marks the mean sea level. All other tidal ranges are referenced from this point. The Fylde has one of the highest tidal ranges in the UK.”
The fun starts when the incoming tide is at its highest, with a strong wind blowing behind it. That’s when it comes over the wall. Add a third factor of low air pressure and it signals even more fun and games. That’s when storm surges can happen – creating really bad storm conditions with lots of overtopping and/or flooding. More about storms below…
This high tide in February 2023 was just a couple of days before the Spring tide –
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Is the beach that you like to use tidal? Does it get covered by water when the sea comes in? If so, you’ll need to check the tide times before setting off with your bucket and spade.
Tide times are published each year for beach users to refer to. You can get the information online or in a handy little booklet called a tide table. If you come to the Fylde Coast frequently (or live here) you might find it easier to buy one. They’re not very expensive and available from the Tourist Information Centre and local newsagents.
If you want to go out on the beach the best time to do it is between high and low water, to follow the tide as it goes out. It gives you the maximum amount of time before it comes back in.
Whatever you do, please take care on the beach and watch out for sandbanks where you might get stranded.
Why does the tide move on each day?
Calder Dale also explained why high tide is about 1/2 hour later each day. “The moon takes 27.3 days to orbit the Earth (in the same direction as the Earth’s spin). So if you sit in your deck chair on Cleveleys prom at high tide the Moon will be straight above you. After 24 hrs you will return to the same point , but the Moon will have moved on a bit in its orbit. If you sit and have an ice cream, the Earth will have caught up with the moon in 50 minutes : so a Lunar day is 24 hrs and 50 mins. Two tides a day so divide the Lunar day in two and you have 12 hrs and 25 mins between each high tide.
“So why two tides a day you might ask… why is there another high tide on the other side of the Earth. That’s because the tide producing force actually squeezes the oceans (like a dig in the ribs) and forces the oceans out on both sides. There is another significant tidal force causing this, other than the variable gravitational forces. The centripetal reaction force is the culprit. That’s enough science… but it gets more interesting as other variables come into play…
A number of beaches along the Fylde Coast remain dry at high water. They’re handy spots for walking, beach sports and playing.
- Ferry Beach at Fleetwood
- Marine Beach at Fleetwood
- Rossall Beach at Cleveleys
- Tiny bit of Blackpool beach near to Central Pier
- The beach fronting the sand dunes at St Annes
- Most of St Annes beach
- Salt marsh fronting Lytham Green
Exactly how much dry sand there is will, of course, depend on the time of year, tide heights and weather conditions on the day.
Don’t forget that whether the sea is in or out you can always walk along the promenade along the whole of the seafront. There’s a footpath along the whole of the Fylde Coast, right against the waters edge. Pick your spot, pitch your deck chair and enjoy the view!
REMEMBER: That bathing beaches are subject to a dog ban during the summer season.
Over December and January of 2013/14 there were two really bad storms in quick succession.
A combination of a very high tide, strong westerly winds and a low atmospheric pressure arrived at the same time. Together it sent the waves flying up and over sea walls all along the Fylde Coast.
- There’s another article here about storms.
How Tides Work – and why the sea comes in and out
It’s the gravitational pull of the moon and the sun, combined with the rotation of the earth, which makes the sea come in and go out each day.
The gravitational effect of the moon as it orbits around the earth ‘pulls’ on the oceans, pulling the water towards the moon to create a high tide.
- The gravitational pull of the moon is stronger than the pull created by the sun.
- But when the sun is in line with the moon, it enhances its gravitational effect. This is why we get higher tides than normal. These are the Spring tides.
- When the sun and the moon are at right angles to each other, their gravitational effect is diminished.
- At this point we get lower tides than normal, the Neap tides.
There’s a lot more to it than this, of course. The daily ebbing and flowing that seems so simple and primeval is actually backed by lots of science and amazing physics.
Would you like to know more?
There’s an article on Wikipedia here with more of the science behind the subject and lots, lots more on the internet.
Take a look through the articles in our environment section and find out more about how weather systems affect us here on the Fylde Coast.
Watch this short video that we found on YouTube. It explains how tides work in a really easy to understand way. It made sense to us anyway!
Have you seen our Coast Watchers project? With the help of Lancaster University and Wyre Council, we’re exploring and recording the life of our shoreline.
Why don’t you join in? Upload your beach, sea and weather photos to the timeline.
While you’re here…
What do you think? Why don’t you join in and leave a comment below?
Have a look at the homepage of the Visit Fylde Coast website for more of the latest updates.
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