When it comes to lighting, the color temperature of white light plays a pivotal role in setting the mood and functionality of a space or other areas of illumination, for instance aquarium or greenhouse lighting. The terminology used to describe these types of white — warm white, soft white, neutral white, natural white, cool white, and cold white — can often be confusing. This blog post aims to clarify these terms.
The Basics of Color Temperature
The Color temperature (or more precisely Correlated Color Temperature – CCT) is a way to describe the color appearance of a light source by comparing its color to the color of light emitted by a theoretical black body when heated to a particular temperature, measured in Kelvin. The idea is that if a light source has a CCT of 3,000K, its color appearance is similar to the light emitted by a black body heated to 3,000K. This provides a standard reference that allows for the comparison of different light sources in terms of their color appearance. It is measured in degrees of Kelvin (K) on a scale from 1,000 to usually 10,000. Essentially, it determines whether the light appears more yellow/gold (warm) or blue (cool). The lower the Kelvin number, the warmer the light, and vice versa.
There are light sources existing with a CCT above 10,000K, but this is in general not considered as a white light. Read more about this further below.
Different types of white light
- Warm White and Soft White
Starting with the warmer end of the color temperature range, warm white and soft white lights emit a cozy, inviting light, typically in the color temperature range of 2700K to 3000K. Mimicking the soft hue of the early morning sun or traditional incandescent bulbs, these lights are ideal for creating a relaxing ambiance. Perfect for living areas, bedrooms, and dining rooms, both warm and soft white lights enhance the feeling of warmth and comfort. The difference between them is subtle, with “soft white” emphasizing a gentle, subdued illumination.
- Neutral White and Natural White
Neutral white lights fall within the 4000K to 5000K range, offering a more balanced light that sits between the warm and cool ends of the scale. Ideal for both residential and commercial settings, neutral white light provides clear visibility without the harshness. Natural white, slightly warmer, typically ranges from 3500K to 4500K, is favored where a comfortable, yet bright atmosphere is desired.
- Cool White and Cold White
At the cooler end of the CCT-range, cool white lights, ranging from 5000K to 6500K, deliver a bright and vibrant light that resembles daylight. This type of lighting is often used in offices and retail spaces and can enhance concentration and alertness. Cold white might be considered an extension beyond cool white, with color temperatures exceeding 6500K, offering an even more blueish light. While less common in everyday settings, cold white can be useful in environments that require intense brightness.
Light sources above 10000K
While the typical color temperature ranges between 1,000 and 10,000 Kelvin (K), there are light sources available with a CCT exceeding 10,000K. These light sources are often referred to as “actinic”. The term “actinic” relates to light that has a high portion of blue wavelengths, which are particularly effective in promoting photosynthesis in plants and are also used in aquarium lighting to support the health of coral and other marine life that rely on photosynthesis. The inclusion of actinic lights in the broader discussion of lighting expands the application of color temperature beyond human-centric lighting design.
Actinic Lights and Their Uses
Actinic lighting is primarily used in specialized applications rather than general lighting. In the context of aquariums, actinic lights simulate the conditions of deep water, providing the necessary spectrum for coral and other marine organisms that thrive under direct sunlight in their natural habitat. The blue light penetrates water more effectively than light of warmer colors, mimicking the oceanic conditions at greater depths.
In photography and the printing industry, actinic light is used because of its consistency and the way it interacts with photosensitive materials. The high Kelvin temperature ensures a light that is crucial for certain chemical reactions in photographic development and printing processes.
How Actinic Lights Fit Within the Color Temperature Spectrum
Actinic lights, with their CCT above 10,000K, represent an extension of the daylight spectrum mentioned in the previous discussion on color temperature. While the typical consideration of color temperature ends at about 10,000K, actinic lights go beyond this limit., offering a spectrum that is richer in blue wavelengths. This doesn’t change the foundational understanding of color temperature but adds a specialized category for applications where specific light qualities are necessary for biological, photographic, or industrial purposes.