Question

Why is $\tt \red{red}$ colour selected for danger signal lights?​

Answer 1

Answer:

Because the red light has the largest wavelength of all colours, it is the least dispersed. Because of this, much of the light gets reflected back and can travel longer distances through clouds, fog, dust etc. to effectively enter our eyes.

Answer 2

Explanation:

As the light travels through the atmosphere, small particles of air scatter it. Because the red light has the largest wavelength of all colours, it is the least dispersed