Solve these clues to fill the grid.
- An imaginary line around the Earth forming the great circle that is equidistant from the north
- 2 Across
- Extensive tract of level open land
- 3 Across
- A continent in the western hemisphere connected to South ___ by the Isthmus of Panama
- 5 Across
- A treeless grassy plain
- 7 Across
- Whether it's rainy, sunny or windy outside
- 8 Across
- Dry land with very little rain
- 11 Across
- The largest ___ in the world
- 12 Across
- Large area covered with trees
- 13 Across
- An imaginary line around the Earth parallel to the equator
- 14 Across
- The chief ___ range of western North America
- 15 Across
- The prevailing psychological state
- 16 Across
- Ground that is ___ frozen
- 1 Down
- The angular distance between a point on any meridian and the prime meridian at Greenwich
- 4 Down
- The 2nd largest ___
- 6 Down
- North American republic containing 50 ___ - 48 conterminous ___ in North America plus Alaska
- 9 Down
- A vast treeless plain in the Arctic regions where the subsoil is permanently frozen
- 10 Down