**Luminosity** is a variable element in the environment to which the driver must constantly adapt. This is because the amount of light can change depending on the time of day, weather, or location. For example, driving at night involves facing conditions of **low lighting**, which can affect visibility and increase driver fatigue.

Unlike luminosity, **vertical signs** and the **geometric configuration of the road** are fixed and predictable elements. Signs are designed to be visible in various conditions and do not change frequently. The structure of the road, such as its shape and design, also remains constant. Therefore, luminosity is the only factor that varies and requires the driver to adjust their driving accordingly.