More tides
04 Feb 2010 Leave a Comment
in The River Tags: earth, moon, tides
Time for a coffee. What better place than here. The sun was so warm l could feel it burning the side of my face. The picture shows the height of the tide compared with yesterday’s pic. I’d be under about 10 metres of water if l was stood at yesterday’s low tide mark.
The tides and how the moon influences them fascinates me.
The key when it comes to understanding how the tides work is to understand the relationship between the motion of our planet and its moon. Both the Moon and the Earth are constantly moving through space. Since the Earth spins on its own axis, water is kept balanced on all sides of the planet through centrifugal force. The Moon’s gravitational forces are strong enough to disrupt this balance by accelerating the water towards the Moon. This causes the water to ‘bulge.’ The Earth’s rotation causes a sympathetic bulge on the opposite side of the planet as well. The areas of the Earth where the bulging occurs experience high tide, and the others are subject to a low tide. However, the Moon’s movement around the Earth means that the effects of its forces are in motion as well, and as it encircles our planet, this bulge moves with it.
Tides occur regularly in the sense that they can be expected twice a day, but their periods do not coincide with the 24 hour day. This is because the Moon takes slightly longer than 24 hours to line up again exactly with the same point on the Earth – about 50 minutes more. Therefore, the timing of high tides is staggered throughout the course of a month, with each tide commencing approximately 24 hours and 50 minutes later than the one before it.
Fascinating eh?
