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Everything Else Bonaire: Weird Science on Bonaire
Bonaire Talk: Everything Else Bonaire: Archives: Archives 1999 - 2004: Archives - 2001-07-02 to 2001-12-31: Weird Science on Bonaire
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Saturday, October 20, 2001 - 11:01 am:     Edit PostPrint Post

I'm almost embarrassed to ask this question, as I suspect any junior high school student should know the answer, but:

Why is tidal activity so minimal? There appears to be a difference of only a foot or so between high and low tides. If memory serves me, the variation is much greater at other locations, such as the east coast of the US.

If you can answer this, I have yet another question for you.

Steve

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Antonio Ferrer on Saturday, October 20, 2001 - 12:59 pm:     Edit PostPrint Post

The question is not simple at all. I don't know much about tides, but I know that there is a wide, wide variation in the amplitude of tides all over the World. The record tides seem to be in the Minas Basin of Nova Scotia (Bay of Fundy), but there are other huge tides. Mount Saint Michel, an Island/peninsula off Normandy, France, is very famous for becoming isolated at high tides. In the Mediterranean Sea, on the contrary, tides are minimal.
Another interesting feature of tides is that they have a pattern that varies with location: in somes areas there are two high tides and two low tides, with regular time intervals (that is what I have allways seen); but in other locations, the intervals are not equal, and in yet other places there is only one tide (low and high) everyday.
Very interesting! If anybody knows a good site on the Internet on this subject, I would be interested to know

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Bea and Marvin Jones on Saturday, October 20, 2001 - 3:26 pm:     Edit PostPrint Post

I found http://www.co-ops.nos.noaa.gov/ which should be a good site. There was an "about" section at the bottom of the home page which included what causes tides (pull of the moon).

HTH - Bea

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Jake Richter - NetTech on Saturday, October 20, 2001 - 4:32 pm:     Edit PostPrint Post

Not a stupid question. From what I've seen, tidal activity becomes more noticable the further you get from the equator. Factors which have to do with tidal activity include the rotation of the Earth (centripedal and coriolis forces, if I recall correctly), seasonal axial tilt of the planet, as well as the moon.

Jake

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Antonio Ferrer on Saturday, October 20, 2001 - 6:35 pm:     Edit PostPrint Post

Jake, I think that local geography is also very important. Some channels and bays just seem to "funnel" the water creating large tides.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Antonio Ferrer on Saturday, October 20, 2001 - 6:37 pm:     Edit PostPrint Post

Thank you, Bea and Marvin, I will lok into it

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Saturday, October 20, 2001 - 8:10 pm:     Edit PostPrint Post

Very interesting site, Antonio - thank you!

I think Jake's on to something, as the distance from the equator does seem to be a factor. One station in Maine had a 20' differential. There are some exceptions, though, as Nome, Alaska, had only about a 2' differential.

Steve

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Saturday, October 20, 2001 - 8:15 pm:     Edit PostPrint Post

Okay....weird science question #2:

I was fascinated that the mirror in our bathroom at Habitat never fogged, and I always take long, steamy showers. I've stayed in hundreds and hundreds of hotel rooms, in many differenct climates, seasons, etc, and I don't recall ever NOT having to wipe the mirror with a towel, in order to shave after my shower.

Why didn't the mirror in Bonaire fog?

Steve

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Carole Baker on Sunday, October 21, 2001 - 1:06 am:     Edit PostPrint Post

Was the air conditioning on or off? Carole

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Keely on Sunday, October 21, 2001 - 1:40 am:     Edit PostPrint Post

Before we go any further down this path, Steve --- could you see your reflection in the mirror?

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Sunday, October 21, 2001 - 9:00 am:     Edit PostPrint Post

Carole...the air conditioner was on, but it was a wall unit, and only in the main room.

Andy...why yes, I could see my reflection quite clearly (a sobering experience, trust me).

Steve

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Antonio Ferrer on Sunday, October 21, 2001 - 10:30 am:     Edit PostPrint Post

Steve, assuming you could see your reflection in the mirror :-) there are only three possible causes for non-steaming of mirrors:
1) The mirror surface is specially treated with an anti-fogging agent (unlikely)
2) The mirror itself is warm enough for the water vapor not to condense - not very likely, but possible in a warm room
3) There is a draught in the room that prevents condensation (carries saturated air away from mirror and outside the room)
Must have been one of these!

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Sarah on Sunday, October 21, 2001 - 2:44 pm:     Edit PostPrint Post

Location is a big factor as far as tides go, in that some parts of the Earth are closer to the moon than others "gravitational force". Then, of course there's the spring and neap tides which also have an effect on tidal activity. S:)

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Anonymous on Sunday, October 21, 2001 - 3:28 pm:     Edit PostPrint Post

and if you could not see your reflection, maybe one of the local blod sucking mosgitoees turned you into a vampire

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Keely on Sunday, October 21, 2001 - 3:34 pm:     Edit PostPrint Post

Right. Having established that you could see your reflection Steve, I don't think you were having an "out of body experience".
I was puzzled for a while after this, but I think Sarah has just come to the rescue.....On our small island we have dramatic rises & falls in sea level caused mainly by the varying gravitational pull of the moon. On "good" days we are so light, that it's hard to keep our feet on the ground. However, on "bad" days (when the moon is furthest away) it's hard to keep our knuckles off the pavement!
Incidentally, this is where the expressions "Feeling light headed" & "Heavy, man!" originated from.
So, whilst it's rare to experience these extremes so near the equator, it's my guess that this is the explanation. ie. you would have either found the water droplets which normally adhere to the mirror, on the floor beneath the mirror, or on the ceiling above it, depending on the negative or positive force the moon was exerting upon them. Phew! Think I might go & lie down for a while.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Sunday, October 21, 2001 - 8:15 pm:     Edit PostPrint Post

Antonio...of your three possible solutions, only #2 is likely. This answer was also suggested by one of friends at Habitat...that the mirror itself is relatively warm (the bath was not air conditioned). Guess that the principle would be the same as the "dew point"...the temperature at which cooling air exceeds 100% humidity, and therefore the humidity condenses.

Andy...your reference to the lingo of the late 60's (Heavy, man!) goes a long, long way to explaining your answer. (I'm still rolling on the floor!)

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Sunday, October 21, 2001 - 8:17 pm:     Edit PostPrint Post

My apologies to Bea and Marvin Jones. I mistakenly gave Antonio credit for the excellent web site they suggested regarding the tides. (I must have had a similar lifestyle to Andy during the late 60's - I wish I could remember what it was).

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Carole Baker on Sunday, October 21, 2001 - 9:16 pm:     Edit PostPrint Post

Bitchin' and far out, man! Way to go, Dude. cb

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Keely on Monday, October 22, 2001 - 1:32 am:     Edit PostPrint Post

Just one last thought on the matter, Steve.
Were you staying in the Habitat's ever popular "Virtual Dive Suite"?
You know ... the one where you & your dive buddy put on your wetsuits (all made of black rubber in the 60's weren't they) & simulate the Heimlich manouvre together on the waterbed?
Well, if you were .... I've heard that Jack's had video cameras mounted behind all the mirrors in the unit. So Antonio could be right ... the heat from the cameras motor could be warming the glass of the mirror.
What's that you say Jack? ... "Your solicitor will be in touch with me shortly?"

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Scott on Monday, October 22, 2001 - 8:02 am:     Edit PostPrint Post

soap film on mirror is a possibility,maybe even likely as it is hard to fully remove and transparent when dry, and very common in motel rooms.
To fully understand tides is to have a complete understanding of astrophysics and wave theory.
I've never understood them fully and have been trying for many decades.(Andy would say I'm not the sharpest knife in drawer)
here in swfl we have from four to one tide(s) in one day, cycles of 5 hours to 24 hours, winter and summer tides are many feet above or below mean and have no relation of course to neap and spring tides. Wind, wave interaction, shoreline configuration also influence time and magnatude of tide. Here in the land of skinny water(you have to go 30 miles offshore to get into 100fsw) we listen every day to noaa, then promptly disregard the info and look out the window, mainly at the moon.
Lunatic(s) I spoze.
There must be a joke in here somewhere.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve and Sandy Oliver on Monday, October 22, 2001 - 8:07 am:     Edit PostPrint Post

Hidden cameras in our Habitat room? hmmm...that would certainly explain the curious looks Jack gave us at breakfast one morning. ;)

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Barry Baker on Monday, October 22, 2001 - 2:28 pm:     Edit PostPrint Post

A friend says the answer to such wide variations in tidal movements would also depend on whether or not the place being measured is an inlet or bay or is an island. Because an inlet or bay channels (or funnels) the water into a shallower and narrower area the tidal flow then becomes more dramatic than on an island where water would have a tendency to move around the island and not up and down the shore. Other factors such as equator and moon affect it also.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Antonio Ferrer on Monday, October 22, 2001 - 6:16 pm:     Edit PostPrint Post

There is a river in England (I think it is the Severn) which has a long estuary where spring tide reaches a considerable distance inland and, by the factors Barry mentions, gives an enormous tidal wave. I have never seen it myself, but I have a vague recollection of hearing stories about this Severn tide.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Hazel Scharosch on Monday, October 22, 2001 - 10:06 pm:     Edit PostPrint Post

...This sounds astonishingly like a fabulous, you guessed it, government grant in the making!!! I would be willing to sacrifice my work with students to properly research the phenomena. Of course, Boanire would be one of my study areas, as well as Bora Bora, which didn't seem to have a tide inside the lagoon at all, hmmm, strange and interesting. I think I'd like to visit that river in England, and Monterey Bay, CA as well.

 

Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Keely on Tuesday, October 23, 2001 - 2:23 am:     Edit PostPrint Post

Yes Antonio. You're right it is the Severen (sometimes better known as the Tsunami!).
Us Brits don't consider anyone should be allowed to call themselves a "real" diver unless they've done a drift dive there. Up to 8 knot currents & nil Viz, but you probably wouldn't want to see anything coming towards you at that speed anyway! Check out www.motorboat.btinternet.co.uk for some interesting facts on the river.

 


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