Which of the following is NOT a wind indicator?

Humidity levels do not serve as a direct indicator of wind direction or speed. Wind indicators are typically physical phenomena that show the movement of air as it interacts with its environment. Foliage movement, for example, allows you to observe how trees and bushes sway with the wind, providing a clear indication of the wind's direction and strength. Similarly, debris and dust movement can help you gauge not just wind direction but also its intensity as small particles are carried by airflow.

Mirage, while it may seem unrelated, can also signify atmospheric conditions influenced by wind, such as heat waves refracting light. However, humidity levels mainly refer to the amount of moisture in the air and do not provide any information about wind's behavior or characteristics. This is why humidity levels are categorized separately and are not considered a wind indicator.