Street Lamps Are Mostly Yellow

- Apr 19, 2019-

Street lamps are mostly yellow because they use sodium lamps (usually high pressure sodium lamps now) that emit light by sodium vapor.

In all kinds of traditional electric light sources, sodium lamp is the highest light efficiency, or in other words, the same light cost of the least electricity. At the same time, the life of the bulb is the longest, reaching more than 20,000 hours.