Theory:

Longitudes
  • Imaginary lines
  • Sketched vertically connecting the North Pole and the South Pole.
  • They are also called lines or meridians of longitude.
  • These lines of longitude are seen as semi circles.
Degrees of longitudes can be divided into minutes and each minute of longitude can be further divided into seconds.
Important!
1° (degree) = 60' (minutes)
1' (minute) = 60'' (seconds)
 
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Important!
Prime Meridian: \(0°\) line of longitude
Number of lines on the either side of Prime meridian:\(180\)lines of longitude
Total lines of longitude:\(360\)lines.
  • These lines converge at the poles.
  • The 180° W and 180° E line of longitude are the same line.
  • Eastern Longitudes: The lines of longitude found between the Prime Meridian(\(0°\)) and the\( 180° \)East line of longitude.
  • Western Longitudes: The lines of longitude found between the Prime Meridian (\(0°\)) and the\( 180°\)West line of longitude.
Two opposite meridians form a great circle.
The lines of longitude are
At Equator:Semi circles covering 111km
At 45° latitude79km
Important!
As the longitudes converge there is no space between them at the poles .
Eastern Hemisphere: The portion of the Earth between the \(0°\) line of longitude and the \(180° \)East line of longitude.
 
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Western Hemisphere: The portion of the Earth that lies between  \(0°\) line of longitude to \(180°\)West line of longitude.
western hemisphere.jpg