# Perceived Height and actual height

• I
Hi all,

I want to calculate the perceived height of a number of mountains.
I know the height and distance from one of the mountains.

If the hieght of the mountain is 925 metres and the distance is 20000 metres away, is there a method of calculating the perceived height for this mountain and then using that, can the perceived height of mountain heights adjacent to it be calcualted also?

PS I know a mountain height if 925 metres does not seem that high but in a country where the highest mountain is just over 1000 metres, it is considered one here

Thank for you help.

## Answers and Replies

Related Other Physics Topics News on Phys.org
PeroK
Science Advisor
Homework Helper
Gold Member
How are you defining "perceived" height?

Last edited:
russ_watters
Baluncore
Science Advisor
2019 Award
If the hieght of the mountain is 925 metres and the distance is 20000 metres away, is there a method of calculating the perceived height for this mountain and then using that, can the perceived height of mountain heights adjacent to it be calcualted also?
For your situation the math is not too difficult. Knowing the range to a peak, and the curvature of the Earth, you can calculate the angle between the horizontal and the peak.

The heights of the Himalayan peaks were all sighted with a theodolite from various known positions in India. The position of the peaks could then be found by triangulation, then the range and elevation angle gave the height of the peak above the observer and so above sea level. All computations were done using an elliptical Earth model.

Lnewqban
Baluncore
Science Advisor
2019 Award
@Howlin
You could use Google Earth. Identify your position as observer. Draw lines from there to each peak of interest. Right click on the line, then select “show elevation profile”. Check that the peak is visible and not obstructed by intermediate topography. Read off the average slope of the line.
That will not allow for atmospheric refraction of the line of sight, which will usually raise distant objects.
https://en.wikipedia.org/wiki/Atmospheric_refraction

See also; Prominence; https://en.wikipedia.org/wiki/Topographic_prominence

Lnewqban
sophiecentaur
Science Advisor
Gold Member
Try this link if you don't like sums.

Baluncore
Baluncore
Science Advisor
2019 Award
Try this link if you don't like sums.
Piltdown effect. The missing link in your post.
My PM to you is blocked.

sophiecentaur
sophiecentaur
Science Advisor
Gold Member
Ye gods. I'm losing it. I'm not blocking people as far as I know. I will have a look.
Here is that link.

Hi all,

I want to calculate the perceived height of a number of mountains.
I know the height and distance from one of the mountains.

If the hieght of the mountain is 925 metres and the distance is 20000 metres away, is there a method of calculating the perceived height for this mountain and then using that, can the perceived height of mountain heights adjacent to it be calcualted also?

PS I know a mountain height if 925 metres does not seem that high but in a country where the highest mountain is just over 1000 metres, it is considered one here

Thank for you help.
NOTE:
The January 2002 issue of National Geographic magazine printed an interesting confirmation of the validity of Meier's claims. In that issue, I found a newsbrief which acknowledges that, just as Meier claimed back in the 1970s, Mt Everest is not the highest mountain on Earth.

Meier, in his writings, stated the Pleiadians told him that Mt Chimborazo in Ecuador was higher than Mt Everest by 2,150 metres because the Earth is not perfectly round but, rather, bulges in the middle-thus, measuring mountains from sea level is not an accurate way of assessing the true height of a mountain.

National Geographic states that scientists have now determined that the Earth bulges around the middle because of the spinning action of the Earth's rotation, and thus, when measured from the center of the planet, Mt Chimborazo is actually higher than Mt Everest by 2,200 metres. Measured from sea level, Mt Everest is 2,540 metres higher than Mt Chimborazo. The newsbrief states that when measured from the centre of the Earth, Mt Chimborazo is 6,384,450 metres high and Mt Everest is 6,382,250 metres high.

A.T.
Science Advisor
The newsbrief states that when measured from the centre of the Earth, Mt Chimborazo is 6,384,450 metres high and Mt Everest is 6,382,250 metres high.
I am also more than 6,000 kilometres high, when measured from the center of the Earth.

Spinnor and sophiecentaur
Baluncore
Science Advisor
2019 Award
The question was about the perceived height of a mountain, viewed from the surface, not measured from the centre of the Earth.

Baluncore
Science Advisor
2019 Award
Mt Chimborazo is higher than Mt Everest in terms of both air temperature and barometric pressure.

The question was about the perceived height of a mountain, viewed from the surface, not measured from the centre of the Earth.
And what is "perceived height"?

Baluncore
Science Advisor
2019 Award
How are you defining "perceived" height?
And what is "perceived height"?
It is difficult for a person to judge the actual distance to a far off mountain. Since range is unsure, the perceived height would need to be measured as an elevation angle, above the observers horizontal. The perceived height would vary with the location of the mountain relative to the perceptor.

The changing refraction of light in the Earth's atmosphere makes the computation more complex.

So this perceived height is the angular elevation above the horizont?
Is this a terms used in a specific field?
When I look it up with Google I get quite different meaning, reffering to people's height.

Baluncore
Science Advisor
2019 Award
Is this a terms used in a specific field?
No, the OP question was poorly worded. The OP has not returned to explain their meaning, so we must read between the lines to reduce the possibilities.

When I look it up with Google I get quite different meaning, reffering to people's height.
Then you should try different search terms.

The OP refers to the perceived height of a number of mountains. Only an angular measure can work when the mountains vary in range from the observer.
Given the height and location of some mountains, how would you predict what the mountains would look like on the horizon, from the observers point of view? A small near-by mountain could appear to be the same angular height as a tall far-off mountain.

I believe that we should rather find out what the question is before answering what we guess it may be the question.
The OP is the one who should explain what he means by "perceived height".

Baluncore
Science Advisor
2019 Award
Since the OP has not returned in the last two weeks with an answer we can but take a well educated guess.

Astronuc
Staff Emeritus
Science Advisor
I want to calculate the perceived height of a number of mountains.
Does one mean prominence, the height of a mountain or hill's summit relative to the lowest contour line encircling it but containing no higher summit within it, or the relative height with respect to some plain?

https://en.wikipedia.org/wiki/Topographic_prominence

Baluncore
Science Advisor
2019 Award
I considered prominance in post #4. But I think we may be looking at the gently rounded hills in Ireland, 44 km South of Dublin. The area has been covered by an ice sheet, so it has lost it's peaks.
Lugnaquilla Mountain, 925 m, Ireland, is the highest peak in the Wicklow Mountains.
Carrauntoohil in Co. Kerry is famous for being the highest peak in all of Ireland as it stands at a whopping 1,038 metres in height.

sophiecentaur
Science Advisor
Gold Member
I remember seeing a film, once, about a village in Wales and the inhabitants transported a vast amount of rock and stone to make their local mountain the hight in the whole -( or some part ) of Wales.

Not the best film I ever saw, I'm afraid but it did lodge in my memory.

Astronuc
Staff Emeritus
Science Advisor
I missed the mention of Prominence, which would seem to fit the use of 'perceived' or 'apparent'. Height and distance are always measured between two points, one being a reference.
But I think we may be looking at the gently rounded hills in Ireland, 44 km South of Dublin. The area has been covered by an ice sheet, so it has lost it's peaks.
Lugnaquilla Mountain, 925 m, Ireland, is the highest peak in the Wicklow Mountains.
Carrauntoohil in Co. Kerry is famous for being the highest peak in all of Ireland as it stands at a whopping 1,038 metres in height.
Coincidentally, I've been watching Secrets of the Irish Landscape on Amazon Prime.
Book - https://www.amazon.com/dp/1782050108/?tag=pfamazon01-20
Video - https://www.amazon.com/dp/B01LG65CAO/?tag=pfamazon01-20

I have to visit Clare Island, among other places. My ancestry goes back to the area around Sligo, as well as the Hebrides and Highlands.