ATPL: The polar front is the boundary between:
Domanda 471, Meteorology - ATPL - Airline Transport Pilot license
| Maritime polar air and continental polar air. |
| Polar air and tropical air. |
| Arctic air and tropical air. |
| Arctic air and polar air. |
| Maritime polar air and continental polar air. |
| Polar air and tropical air. |
| Arctic air and tropical air. |
| Arctic air and polar air. |
