Pick up the correct statement from the following:
- AOne degree of longitude has greatest value at the equatorCorrect
- BOne degree of longitude has greatest value at the poles
- COne degree of longitude has the same value everywhere
- DOne degree of latitude decreases from the equator to the poles
Solution
Concept
Length of a degree of longitude
Formula
Length of 1° of longitude = (π/180) R cos φ
Step-by-step solution
1. Meridians converge towards the poles. 2. So the distance between two meridians 1° apart is largest at the equator (about 111 km) and zero at the poles.
Explanation
The length of one degree of longitude decreases with latitude as cos φ, being maximum at the equator and zero at the poles. One degree of latitude is almost constant (about 111 km), increasing very slightly towards the poles.
Shortcut
Longitude degree ∝ cos(latitude).
Common mistake
Mixing up the behaviour of latitude and longitude degrees.
Correct answer: A) One degree of longitude has greatest value at the equator