"When the two highs and the two lows are about the same height, the pattern is called a semi-daily or semidiurnal tide. If the high and low tides differ in height, the pattern is called a mixed semidiurnal tide. Some areas, such as the Gulf of Mexico, have only one high and one low tide each day. This is called a diurnal tide".
So here in La Manzanilla we have a mixed semidiurnal tide.
Low and high tides are mostly caused by the gravity of the moon and the sun, when the moon and sun are aligned as they were on December 10 we get very high
And very low tides
But starting Wednesday to the end of the week there is really only one low and one high tide per day. What would normally be a low tide has changed into a little bump.
From what I gather that is due to the position of the sun and the moon (which are far from aligned) as shown below.
Here is a video of the solar system from December 10 2015 to January 10 2016 30 days, one revolution of the moon around the earth
You can go here and increase the resolution to HD and go full screen if you want to really see our planet going through the solar system for one month.
Posted by Red on December 30, 2015, 7:50 am, in reply to "Interesting tides" 189.164.110.5
Nice work D, thanks. Rojo
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Re: Interesting tides
Posted by Randy on December 30, 2015, 12:15 pm, in reply to "Interesting tides" 75.106.61.119
I like this. But if the moon is a major factor you would expect the times to be about 50 minutes later each day, as the moon rises 50 minutes later each day. These tides are going backwards, earlier each day. So there is some further complication, yet it's predictable. Anybody have any idea? By the way, I've been on the gulf coast of Mexico, and not only is there one tide per day, it's at the same time every day. How can that happen?
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Re: Interesting tides
Posted by Daniel H on December 30, 2015, 2:35 pm, in reply to "Re: Interesting tides" Edited by board administrator December 30, 2015, 2:39 pm
Hi Randy, your post is in quotes.
"But if the moon is a major factor you would expect the times to be about 50 minutes later each day, as the moon rises 50 minutes later each day."
Since there are two tide cycles the difference is about 25 minutes each cycle.
"These tides are going backwards, earlier each day".
The moon goes around the earth one time per month, which means it moves a little (12 degrees) every 24 hours. I made a drawing below to help explain it to you (an myself).
X is us in La Manzanilla looking up at the moon #1. 24 hours later we are back where we started but the moon is now in position #2 since it has gone one day in its 30 day journey around the earth.
The tides are a little different than they were last time we were at #1. Since the tides change according to the moon it is 50 minutes earlier in moon time (so to speak).
"By the way, I've been on the gulf coast of Mexico, and not only is there one tide per day, it's at the same time every day. How can that happen?"
Here is the tide chard for Guymas, the times do change. There is only one high and one low tide for each day because the surrounding land mass makes the transfer of the open ocean tides more difficult.