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What is "Sea Level"?
What is "Sea Level" as used in describing the height of a mountain?
What is "Sea Level" as used in describing the height of a mountain?
Originally posted by nautica
Sea level is just what it says. It has arbritrairily been defined as zero, which is the level of the sea.
Nautica
Ok, so you are standing on top of Everest, how do you know how far above sealevel it is? How do you know how far the sea is above sealevel, anyway?Originally posted by LURCH
It's averaged out for tides.
Originally posted by Monique
Ok, so you are standing on top of Everest, how do you know how far above sealevel it is? How do you know how far the sea is above sealevel, anyway?
For instance the Mediteranian sea, it is in connection with the Atlantic ocean through a small opening: the Street of Gibraltar.. does it mean that the Mediteranian sea is always at sealevel? (minimal effect of tides?)
But then I observed that Lake Erie in the US seemed to even have tides..
Yeah, so I went to the beach today (I did).. say I wanted to measure how much the water was above set sealevel, or below, because of tides.. how would I do that? I mean.. what is the reference??Originally posted by nautica
Sea Level is set to zero. It does not matter what tides do, the sea level measure does not change. I am sure if you wanted to take the time to do the calculations you could find the height of the tides due to the moon and the sun at any given time and find the exact hight of the sea. Or you could just use a gps and find it out.
Nautica
Originally posted by Monique
Yeah, so I went to the beach today (I did).. say I wanted to measure how much the water was above set sealevel, or below, because of tides.. how would I do that? I mean.. what is the reference??
Well, that makes sense :)Originally posted by LURCH
That's what I mean by "averaged"; find however high the water gets at high tide, and however low it gets at low tide, determine the average between these two, and that is Mean Sea Level.
No, sea level is a local thing and you build your 3d model based on local sea levels.Originally posted by Monique
Well, I really don't get it how can you measure that the water along the coast of Holland is of the same level, as the water along the coast of Australia.. halfway around the world?
Is there somewhere on the world a beacon which says: this is sealevel? Like there is the Greenwhich timezone, which says: this is t0?
Originally posted by Bystander
http://www.gmat.unsw.edu.au/final_year_thesis/p_epstein/monitr_t.htm
Yes, we do have solar tides. Really, gravitational interaction of any two bodies creates tidal forces in both.HERE is a decent site on ocean tides.Originally posted by Monique
How about solar influences? If there were no moon, would we have solar tides? Theoretically how large could those be? How large are lunar tides anyway?
Yes, the position of the moon has a significant effect on the tides. To get a really good sea level average you need a pretty long time period (a year or so).So how complicated would they have made the calibrations? Say for Holland and Australia.. would the position of the moon be significantly different averaged for the same few days at the same locations?
Monique said:Is there somewhere on the world a beacon which says: this is sealevel? Like there is the Greenwhich timezone, which says: this is t0?
Standard commercial GPS is less accurate for the vertical axis, but its gotten a ton better with DGPS & WAAS.ray b said:GPS is NOT accurate enuff for hight data as it has the biggest error rate
about 10x the error rate of the x+y location data for the z hight axis
That second link is very interesting. Actually I just remember now.. a few weeks ago there was a very stormy western wind. I was at the west of the IJsselmeer (a lake) and the water level was SO low! that you could actually go down and walk on the bottom of the lake for a considerable length from the bank.. reminded me of that tale where the water parted and Jesus walked across a lake.. sounds very possible in such a scenarioAndre said:some usefull links for Dutch sea level history:
http://www.ncg.knaw.nl/SubBZ/BeginSubBZ.htm
http://hanserren.cwhoutwijk.nl/co2/denhelder.html
Sea level is the average height of the Earth's oceans and is typically measured in relation to a fixed point on land. This fixed point is known as a vertical datum, and the most commonly used one is the mean sea level (MSL) which is based on the average height of the ocean's surface at a given location over a period of time.
Mountain height does not directly affect sea level. Sea level is determined by the volume of water in the oceans, which is affected by factors such as melting glaciers and ice sheets, changes in ocean currents, and thermal expansion of seawater due to climate change. However, changes in mountain height can indirectly impact sea level by altering the Earth's gravitational field and causing changes in ocean circulation.
The perceived height of a mountain can vary depending on the observer's perspective and the surrounding terrain. For example, a mountain situated near a large plateau may appear shorter compared to a mountain of the same height located in a flat area. Additionally, the shape and steepness of a mountain can also influence its perceived height.
Yes, sea level can change over time due to a variety of natural and human-induced factors. Natural factors include changes in the Earth's climate, tectonic movements, and variations in the Earth's orbit. Human activities such as greenhouse gas emissions and land use changes can also contribute to sea level rise.
Understanding sea level is crucial in predicting and mitigating the impacts of climate change. Rising sea levels can lead to increased coastal flooding, erosion, and saltwater intrusion into freshwater sources. By studying and monitoring sea level changes, we can better prepare for and adapt to these potential impacts. Additionally, understanding the relationship between sea level and mountain height can also help us understand the Earth's overall climate and how it may change in the future.