DLP Flashcards
What are the North pole co-ordinates?
81 degrees N, 110 degrees W
What are the South pole co-ordinates?
65 degrees S, 139 degrees E
Define True North
The true direction of the geographical pole, used for Headings, track and bearings.
Define compass North
The direction indicated by a freely suspended compass needle under the influence of both the Earths magnetic field and other magnetic fields in the vicinity e.g. wiring.
What is the equator?
A great circle which lies midway between the North and South geographic pole. It is perpendicular to the axis of rotation.
What is a nautical mile?
The length of the arc of a great circle subtended by an angle of one minute from the centre of the Earth.
How many feet is one statute mile?
5280ft
How many feet in 1km?
3280ft (A km is 10,000th of the length from the equator to either poll.)
What is spot elevation?
Shows the exact elevation above MSL. Generally used for outstanding peaks.
What is layer tinting?
Colouring the gaps between the contour lines. Normally orange-brown is used for land and blue for sea but a key will show this on the map.
What is hatchuring?
Short tapering lines drawn on a map such that they radiate from peaks. Usually used with spot elevation to show the shape of the peak.
Define magnetic North
The direction of North indicated by a freely suspended compass needle which is only under the influence of the Earths magnetic field. Normally used to measure the direction of flight.
What is deviation?
The angular difference between magnetic North and compass North.
What is hill shading?
Used to give a 3D effect, shading on the map as if there’s a light on one side of a peak, casting shadows.
What is variation?
The angular difference between the direction of true North and magnetic North.
