Why are street lights darker when it rains?

The reasons why street lights are darker on rainy days are as follows:

First of all, rainy weather will cause more water vapor in the air, which will cause light to scatter during the propagation process. The scattering of light in water vapor will change the propagation direction of the light, making the lighting range of the street lamp blurred and uneven. Therefore, the lighting effect of street lights in rainy weather will be relatively poor.

Secondly, rainwater in rainy weather will adhere to the street lamp shade and form a water film. This layer of water film will block the transmission of light, reducing the lighting brightness of the street lamp. At the same time, the water film will also cause light to reflect, thus causing the lighting range of the street lamp to become smaller. Therefore, street lights in rainy weather will appear dim.

In addition, raindrops in rainy weather will continue to fall on the street lamp shades, forming water droplets. These water droplets scatter light and change the direction of light propagation, making the lighting range of the street light blurry and uneven. At the same time, water droplets will also absorb and reflect light, reducing the lighting brightness of street lights. Therefore, street lights in rainy weather will appear dim.

Finally, rain in rainy weather will make the road surface slippery, thereby increasing the reflected light of the street lights. These reflected lights can make the illumination range of street lights blurry and uneven. At the same time, slippery road surfaces will also reflect light from other light sources, reducing the lighting brightness of street lights. Therefore, street lights in rainy weather will appear dim.

To sum up, the reason why street lights are darker in rainy weather is mainly due to the increase in water vapor in the air causing light scattering, the water film and water droplets formed by rain blocking and scattering light, and the slippery The influence of factors such as reflected light from the road surface. These factors make the lighting effect of street lights poorer, resulting in darker street lights.