What really is Sea Level?

[zdas04]

At lunch today my wife asked me "if the sea level rises, will Denver be at a lower elevation?" I stammered a bit and said that sea level is a fairly arbitrary plane equidistant from the center of the earth, blah, blah, blah. She didn't buy it, she wanted to know if the earth warmed up (for whatever reason, not necessarily AGW) and Florida was under water, Little Rock was a beach front community, etc, would "they" change the official elevation of Denver?

My reasoning was that you don't really measure the elevation above sea level, you measure the height of gas above a point to determine atmospheric pressure (and subtract that from official sea level pressure to get elevation) and that what we really measure is height below space. Not sure that she bought that either. Anyone have another explanation?

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[CorBlimeyLimey]

Any photos?

 

[BigInch]

Maybe not, since the spheriod would also attract more atmosphere towards the equator than at the poles (and Everest's latitude). More mass there means more gravity is there too.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[dgallup]

Don't forget "glacial rebound". As the glaciers melt the earths crust is relieved of all that weight pushing it down and the land rises. It's still going on around the northern great lakes from the last ice age.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[btrueblood]

Gravitational acceleration is LESS at the equator than at the poles, due to the centripetal accelerations from Earth's rotation. It's why Ariane built their launch site in Guyana. That said, gravity (or centripetal acceleration) doesn't have as much affect on air pressure as does weather, see

http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/zonal_mean.html

 

[Latexman]

At the time I had no idea on altitude. After looking on wikipedia, I'd say we were about 5,000 meters. I haven't seen those photos in years. They are in our "running from hurricane" photo bin. Finding them is a project for another day. Now that I think about it, we went to Quito from Guayaquil by way of Riobamba, where we spent one night. The next morning is when we went to Chimborazo.

Good luck,
Latexman

 

[Skogsgurra]

I just made a short tour around the World to find out where the coastlines are at.
Seems to be pretty consistently at 0 m "above" sea level. Except for one place in Bangladesh where the coastline seems to be at +11 m. I think that it isn't always easy to discriminate between water and land. Could also be a result of extreme tide.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[vpl]

zdas -- The answer your wife was looking for was "yeah, probably." Then you could have gone into the scientific explanation and her eyes would have glazed over and you would have escaped.

Or you could have gone with the North Carolina explanation that global warming isn't occurring and therefore sea levels aren't rising and no one is to tell them differently. By this approach, the Denver elevation will always be same and she shouldn't worry her pretty little head about it. <warning you would know best about the advisability of this approach and how likely you are to live through it.>

Patricia Lougheed

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[zdas04]

Patricia,
40 years ago when we were newlywed I might have fallen for that one and had a reasonable chance of surviving. We've both evolved and the chances of me saying that or surviving having said it if I did are both near zero today.

Neither one of us dispute that there is data showing that the earth seems to be in a warming cycle. There never has been a time that it wasn't either warming or cooling. We both have a real problem with the trumped-up rhetoric and manipulated computer models that passes for &quot;proof&quot; that human activities is causing/accelerating the change. Or that the change is bad. Or the definition of &quot;bad&quot; (every single global change has winners and losers, a warming period has a lot more winners than losers, and no I don't care if New Orleans is under water, Amsterdam and Venice both survived the last long warming period and thrived so I'm not terribly concerned about them either).

David Simpson, PE
MuleShoe Engineering

&quot;Belief&quot; is the acceptance of an hypotheses in the absence of data.
&quot;Prejudice&quot; is having an opinion not supported by the preponderance of the data.
&quot;Knowledge&quot; is only found through the accumulation and analysis of data.

 

[VEBill]

due to the centripetal accelerations from Earth's rotation

Really?

 

[msquared48]

David:

"Newlyweed"? HMMMMMMM.....

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Skogsgurra]

Shall we also discuss stalgamites and stalactites?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

Amsterdam and Venice both survived the last long warming period and thrived so I'm not terribly concerned about them either).

You should be. Venice is, and has been sinking, all on its own.

http://www.pbs.org/wgbh/nova/tech/saving-venice.html

So, whatever happened in the past, this time it will be worse.

TTFN
faq731-376

 

[Skogsgurra]

That's bad underpinning. Has been a problem ever since.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[patprimmer]

Bad underpinning is even worse when it's only on one side of a tower. At lest my opinion is leaning in that direction.

Regards
Pat
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[zdas04]

Mike,
Shouldn't mock the guy with edit abilities.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[patprimmer]

Mike

You should see what your about to have said. Talk about embarrassing! ;-)

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[VEBill]

While "you're"/"your" editing... !!!

 

[evelrod]

Well, if every altitude on maps were listed differently... My house is listed as 1300' AMSL...

Global climate change is an undeniable fact. Is it cyclical? Probably. Is the advent of the industrial revolution and a gazillion more heavy breathers a factor? Probably. Does this mean that I need to get a set of 'waders'? Probably not.

ROD

 

[IRstuff]

"Does this mean that I need to get a set of 'waders'? Probably not."

I wouldn't be so cavalier. Even though you're at a high altitude, the unwashed masses at the flood altitude are going to want to move to higher ground, so make sure that moat is well filled and the oil drums are ready...

TTFN
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