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Author Topic: PORTOLANS  (Read 3405 times)
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Posts: 41646

« on: September 30, 2007, 07:54:57 am »

Useful Information

Parallels: Circles parallel to the equator, ranging from 0 to 90 N or S. Only the equator is a great circle.

Meridians: half-Circles conversing at the poles, ranging from 0 to 180 E or W. Each pair of meridians forms a great circle.

Prime Meridian: 0 or the Greenwich meridian which divides the Western and Eastern hemispheres.

Great Circle: The intersection of a sphere and a plane through its center.

Small Circle: The intersection of a sphere that does not pass though its center.

Time Zones: By convention 24 zones, each 15 longitude wide. Hence, noon at greenwich gives midnight at 180 E.

GMT: Greenwich Mean Time or UTC or Zulu, and is the time in Greenwich. Antonym: Local time. Berlin's local time = GMT + 1.

Date Line: The meridian which extents from the prime meridian. Here, not only the hour changes, but also the date.

Latitude: Position property defined by the number of degrees North or South of the equator, varies from 0 to 90.

Longitude: Position property defined by the number of degrees East or West of the prime meridian, varies from 0 to 180.

Position: Latitudes first and Longitudes second. For example: Nijmegen (NED) = 51 50',1 N , 05 52',0 E.

Nautical Mile: One nm is one minute (') on the chart. 1' equals 1.852 meters.

Knots: Nautical miles per hour.
« Last Edit: September 30, 2007, 07:57:25 am by Bianca2001 » Report Spam   Logged

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