Exercise Midnight Sun - Greenland 2008
Latitude and Longitude - A simple guide
In Greenland this is the most common form of position reporting and the one that you are most likely to use when on the ground as a member of “Midnight Sun”.
LATITUDE: This the arc of a Meridian measured from the equator to a given point, ie: YOUR POSITION. (A Meridian is half of a circle which passes through both poles). This measurement is expressed in DEGREES, MINUTES and SECONDS North or South of the equator. (Figure 1).
LONGITUDE: This the arc also expressed in DEGREES, MINUTES and SECONDS East or West of the Prime Meridian otherwise known as the Greenwich Meridian. Longitude can never be greater than 180 Degrees East or West because the Prime Meridian bisects the Earth. (All Meridians in fact do this but the Prime or Greenwich Meridian provides our point of reference). (Figure 2).
By convention the group of figures representing Latitude is always written first and is then followed by the figures representing Longitude. (This as you will be aware is the opposite of the way that you would express a Grid Reference). To avoid ambiguity, the figures below ten are preceded by a zero. (Figure 3).
A position in Latitude and Longitude is expressed as a seven or an eleven figure reference:
a.) 52N 007W (7 Figure)
b.) 5248N 00730W (11 Figure)
The unit of measurement for distance on a Mercator Chart is the Nautical Mile, (nm), this is the average length of one minute of latitude. (1nm = 1.852km)
When plotting or measuring distance on a Mercator Chart, due to the expansion of scale from the equator towards the poles, distance must be measured on the margin scale, adjacent to the latitude about which your intended track is to take place.
If this has whetted your interest you can get further info’ by GOOGLING “latitude and longitude” or a very good site with excellent links and an idiot’s calculator is: www.satsig.net.
Good luck and see you there - Wiggy