What is the best method for estimating low surface wind speed?

The best method for estimating low surface wind speed is to utilize characteristics such as the movement of very low clouds, which are sensitive indicators of wind at lower altitudes. Very low clouds, often found in the vicinity of the surface, can provide visual cues regarding the wind strength and direction. Their movement reflects surface wind conditions, making this observation particularly useful.

Pilot reports also contribute valuable information about wind conditions, but they may not always reflect real-time changes or localized phenomena at the surface level. Thus, while they are helpful, they are not the most direct method for estimating wind speed at low altitudes.

A non-moving wind vane would not provide any useful data, as a stationary wind indicator signifies calm conditions or a lack of sufficient wind; therefore, it cannot offer an estimate of wind speed.

Overall, the best method combines visual observations of low clouds along with understanding atmospheric conditions, making the original assessment of option D inaccurate. The context of the weather and the behavior of clouds in the atmosphere is essential for determining low surface wind speeds effectively.