If you have ever flown into a city at night time, other than a nightlife city such as New York or Las Vegas, you can see street lighting that varies in colors from yellow, to white to blue. The reasons for the differences in color are related to how they are manufactured. When you go into a shopping center, the stores have lamps which help to set the moods and actually can influence shopping behavior. In an office, the colors can influence work performance.
There was a scale developed by an Irish physicist, William Kelvin, who heated iron to different temperatures, such as reddish-yellow to white to a bluish color. This scale is how we describe the colors of light used in today’s industry. 2700K is a warm color that is in the red-yellow range and is known as warm white, 4100K is a cool color know as cool white and 5000K is in the blue area, known as daylight. There are numerous intervals below and above these increments and based on the type of lamp, they can be fine-tuned for specific applications.