What aspect of atmospheric conditions does a transmissometer specifically assess?

A transmissometer is an instrument designed to measure the amount of light that passes through the atmosphere, which directly correlates to visibility. The primary function of a transmissometer is to assess how much particulate matter, such as dust, smoke, fog, or precipitation, is present in the air, as these factors impact how far one can see. This measurement is essential for aviation operations, as visibility conditions can significantly affect flight safety and operations.

Temperature, humidity, and pressure are all important aspects of atmospheric conditions, but they do not specifically relate to the measurement of visibility in the same way that a transmissometer does. Understanding visibility is crucial for effective airside operations at airports, where safe distance and sight lines are necessary for vehicle and aircraft movement.