How are runways identified on an airfield?

Runways are identified using numbers that correspond to their magnetic compass heading, rounded to the nearest ten degrees. For example, a runway aligned approximately north (10 degrees) would be identified as runway 01, while a runway aligned approximately south (190 degrees) would be designated as runway 19. This numerical designation helps pilots quickly understand the orientation of the runway relative to the earth's magnetic field, which is critical for navigation and landing.

The other options, while related to airfields and runways in different contexts, do not serve as the primary identification method. Letters representing direction can be used for taxiways and other related features but are not specifically for runways. Lights along the edges of the runway help in visibility during low-light conditions but do not serve as a means of identifying the runway itself. Similarly, while colors may be used for marking different types of areas on the airfield, they do not function to indicate the runway's number or orientation. Thus, the numerical identification based on compass degrees is the most accurate and universally recognized method for identifying runways on an airfield.