| A | B |
|---|
| atmosphere | the shell of gases that surrounds the Earth |
| hydrosphere | the liquid portion of the Earth including the oceans, streams and groundwater |
| lithosphere | the solid portion of the Earth including the crust and upper mantle |
| oblate spheroid | the nearly spherical shape of the Earth |
| coordinate system | a system used to locate positions |
| latitude | the angular distance in degrees north or south of the equator |
| longitude | the angular distance in degrees east or west of the prime meridian |
| parallel | a line of constant latitude |
| meridian | a line of constant longitude |
| equator | line of 0 degree latitude, halfway between north and south poles |
| prime meridian | line of 0 degree longitude; runs through Greenwich, England |
| Greenwich Mean Time (GMT) | the time on the prime meridian |
| field | a region of space in which a similar quantity can be measured at every point or location |
| isoline | a line connecting points of the same value within a field |
| contour map | a map showing an elevation field; a topographic map |
| contour interval | the difference in height between two adjacent contour lines |
| profile | a side view of the changes in field value between two points |
| gradient | the rate of change in field values between two points |
| magnetic declination | the difference in degrees between magnetic north and geographic north |
| anomaly | a data point or value that does not fit the rest of the data |
| altitude | angle measured above an observer's horizon |
| Polaris | star located almost directly above the North Pole |
| geographic poles | poles determined by the Earth's axis of rotation |
| magnetic poles | poles determined by the Earth's magnetic field |
| scale (of a map) | ratio between distance a map to the actual distance on the real Earth |
| relief (of a map) | difference in elevation between the highest and lowest points |
