Longitude conversion according to your latitude

In summary, to calculate the distance between two points on a map, one would use the latitude and longitude of the points and calculate the circumference of a circle using the radius of the Earth and the cosine of the angle of latitude. This would give the difference in longitude.
  • #1
michael atlas
8
0
I have two latitude/longitude points. They are really close together. What I want to do is find the difference between the two longitides and calculate how many yards that would be. If I did the calculation with with the two latitudes, it would be just 2025yds per minute of latitude. However, for the longitude; being that the closer you get to the poles, the closer the lines of longitude move together, you have to apply a conversion to it.

If my lat/longs were 34.34°W, 79.1°N and 34.23°W, 80.3°N Respectively, I want to find the exact amount of yards between my two lines of longitude.

If anyone had the formula to find out how many yds per minute of longitude according to what latitude I am at, I would greatly appreciate it.

Thanks,
Mike
 
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  • #2
Can you not use the second formula I gave you in the other thread?

The radius of any circle of latitude (rθ) is given by the mean radius (r) of the Earth times the cosine of the angle of latitude (θ)

rθ = rcosθ

And by the way what is your application here and there ?
 
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  • #3
My application is for sonar work, programming in matlab.

When I get the answer from the other thread... I just multiply that latitude by 2025yds per degree of latitude AND longitide?

Is that true, because of the fact that I have to convert longitude given the latitude for Theta E
 
  • #4
michael atlas said:
If my lat/longs were 34.34°W, 79.1°N and 34.23°W, 80.3°N Respectively, I want to find the exact amount of yards between my two lines of longitude.


At what latitude? 79.1°N or 80.3°N or somewhere in the middle?

This can all be solved quite easily if you have a good grasp of spherical co-ordinates.
 
  • #5
The difference in longitude is the distance along a parallel of latitude.

Each parallel of latitude is a circle of radius rθ = r cos(θ)

So the circumference of that parallel is 2∏rθ in yards or metres or whatever and 360 degrees in angle.

So for instance the difference between 10° west and and 20° west is 10°

So this in yards is

10/360 times circumference = (10/360) * 2∏rθ where r is the mean radius in yards.

Now the latiture you use for θ is different for each point so you should take the average latitude by adding up the two latitudes and dividing by 2.

Does this make sense?
 
  • #6
Yes it does.

Appreciate it.
 

1. What is longitude conversion according to my latitude?

Longitude conversion according to your latitude is the process of converting a specific longitude value to its equivalent value at a different latitude. This is necessary because the Earth is not a perfect sphere and its shape changes depending on the latitude. Longitude conversion takes into account the curvature of the Earth to accurately determine the longitude at different latitudes.

2. Why is longitude conversion important?

Longitude conversion is important because it allows us to accurately determine locations on the Earth's surface. It is especially useful for navigation and map-making, as well as for scientific research and data analysis. Without longitude conversion, it would be difficult to accurately measure distances and determine precise locations on Earth.

3. How is longitude conversion calculated?

Longitude conversion is calculated using mathematical formulas that take into account the Earth's shape and curvature. The most common method is the Mercator projection, which uses a cylindrical map to represent the Earth's surface. Other methods include the Lambert conformal conic projection and the Transverse Mercator projection.

4. Does my latitude affect my longitude?

Yes, your latitude does affect your longitude. The Earth's circumference is widest at the equator and gradually narrows as you move towards the poles. This means that a degree of longitude at the equator is longer than a degree of longitude at the poles. Therefore, the same longitude value at different latitudes will have different lengths.

5. Can I use longitude conversion for any location on Earth?

Yes, longitude conversion can be used for any location on Earth. The formulas and projections used for longitude conversion are designed to work for any latitude and longitude coordinates. However, the accuracy may vary depending on the method used and the curvature of the specific location on Earth.

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