By: Blonde Two
Whether you experience the sea (and our lovely estuaries) on holiday or as a local attraction, you probably enjoy the tides and the ‘never-the-same-twice’ impact they have on our coastline. I love to swim at high tide and explore at low tide so, for today’s Tuesday’s Ten, I thought I would bring you ten things about the tide.
- The tides are caused by the Earth’s position in relation to other celestial bodies. The gravitational pull of both the sun and the moon drags water, creating a tidal bulge and a high tide. The Earth is also subject to gravitational pull and this has additional impact on the tide.
- In the UK we usually have two high tides and two low tides per 24-hours. This is a semi-diurnal tide cycle. Some places in the UK have unusual tide patterns. For example the Solent’s tides are influenced by the East/West orientation of the English Channel and the Isle of Wight.
- The large landmasses of the continents have an impact on the tides. These can result in a diurnal tide cycle (one high tide and one low tide in 24-hours) in some places, for example, the Gulf of Mexico.
- Spring tides are when the water movement is greatest (creating very high and very low tides). They occur when we have a full or new moon, when the Earth is in line with both the moon and the sun and their gravitational pulls are working together.
- Neap tides are when the water movement is least (resulting in less difference between high and low tides). They occur twice every lunar month, when the moon and sun are at right angles to each other in relation to the Earth and their individual gravitational pulls are working against each other.
- The tide doesn’t ebb (go out) or flow (come in) at an even rate. 1/12 of the water will move in the hour just after high or low tide, a further 2/12 in the second hour, 3/12 in the third and fourth hours, 2/12 in the fifth hour and then 1/12 in the six and final hour. This is known as the rule of twelfths and, in simple terms, means that the amount of tidal water movement will be greater at mid tide than it is at either low or high tide.
- Slack tide is that time at either high or low tide when there is a lull in water movement.
- Weather patterns such as strong winds and changes in atmospheric pressure can affect the height of the tides.
- Geography also influences the tides. The UK’s largest tidal range is in the Severn Estuary and is can reach up to 15 metres. The highest tidal range in the world (16.3 metres) is in the Bay of Fundy in Canada.
- RNLI statistics tell us that over half the 190 people (2017) who are killed in UK waters each year, never intended to be in the water. Always check local tide times before walking along rocks, beaches or tidal rivers.
- In the UK around