Which environmental factors can affect the accuracy of speed measurement?

The accuracy of speed measurement can be significantly influenced by various environmental factors, and the correct choice identifies several critical elements. Rain, fog, wind, and ambient temperature can impact the performance of speed measurement devices, such as radar and lidar equipment.

Rain can absorb or scatter the signals used in speed measurement, leading to inaccurate readings, while fog can similarly interfere with the visibility and effectiveness of these devices. Wind may cause erratic movement or instability for handheld devices or during vehicle-mounted measurements, impacting the consistency of the readings. Ambient temperature can affect the electronic components of speed measurement devices, potentially altering their calibration and performance.

While the other options do mention factors that might have some impact, they do not collectively address as many significant environmental influences on measurement accuracy as the ones specified in the correct answer. Humidity and altitude, for example, can play a role but are less commonly discussed in the context of direct impact on speed measurement compared to the effects of rain and fog. Similarly, light levels and road surface textures might affect visibility or device operation but do not directly correlate with measurement accuracy in the same way as the factors mentioned in the correct choice. Time of day and traffic volume are more about operational context than direct impacts on measurement technology.