What type of security lighting is known to have a yellow hue?

High-pressure sodium lights emit a distinctive yellow hue, which is a result of the sodium gas used in their operation. This type of lighting is commonly used in security applications because it is effective in illuminating large areas and penetration through fog or rain, making it particularly useful for outdoor security settings. The warm yellow light helps in reducing light pollution compared to other types of lights, and there is a specific advantage in how it affects the visibility of certain colors.

In contrast, incandescent lights produce a warmer, more golden light but do not have the specific yellow tint associated with high-pressure sodium lights. Fluorescent lights typically emit a cooler, more bluish-white light. Mercury vapor lamps produce a bluish-green light, which is visually distinct from the yellow hue of high-pressure sodium lights. This differentiation is crucial for understanding the various applications of lighting in security and outdoor environments.