Latitude & Longitude
If this site was about sailing, longitude & latitude would be of great interest as they are the true global co-ordinates. However, for the purposes of the UK mountains a bit of info is included here for completeness.
The basics: the Earth is round (well, it's not quite, but we'll pretend it is for the purposes of brevity!) Lines drawn from pole to pole are longitude, and horizontally (including the equator) are called latitude. There are 360 lines of longitude, each being called ‘a degree’, with 60 sub divisions being called ‘minutes’, and 60 further subdivisions called ‘seconds’. There are 180 lines of latitude.
The following video is an excellent explanation of Latitude & Longitude.
Co-ordinates for Hill Walking
For hill walking and maps used for hill walking, the co-ordinate system used is not degrees, minutes and seconds as described in the video, but a separate one which is based on the British National Grid
In Northern Ireland, there is a separate grid system, based the Irish National Grid
. At this time this site does not go into any detail about Northern Ireland maps or grid systems.
Latitude & Longitude on Walking Map
There is limited information on Ordnance Survey maps about latitude & longitude, but you will find both shown on the edge of your map, printed in black and towards the edge of the printed area of the map. On the mapped area itself you will not find latitude & longitude grid lines, but on 1:50,000 maps you will see the occasional blue cross randomly floating in the middle of the map, which indicates intersection of minutes. At a push, you could calculate broad latitude & longitude co-ordinate from a walking map.
If you have a Longitude/Latitude co-ordinate and want to convert to British National Grid
, or vice versa, you can do that here
Header image courtesy of Open University Creative Commons Licence