Exercise:

Alderney, in the Channel Islands, has longitude 2°W, latitude 50°N.
Winnipeg, in Canada, has longitude 97°W, latitude 50°N.
How far apart are they, in nautical miles, along a parallel of latitude?

Distance along a parallel of latitude is (difference in longitude) x cos(latitude)
= (97° - 2°) cos(50°) = 61.06°

But 1° = 60 nautical miles.

So the distance is 61.06 x 60 = 3663 nautical miles.

Back to "The Terrestrial Sphere".