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Color temperature


What is Color Temperature?

Color temperature is a term used in many technical and artistic fields.
But what does it exactly mean?
Color temperature describes the spectral composition of light and is a way to quantitatively describe the color of light. It is expressed in the unit Kelvin (K).

Units of Color Temperature

The Kelvin scale starts at zero, which corresponds to absolute zero or -273.15 degrees Celsius. A high color temperature indicates a "cooler" or "bluish" light, while a lower color temperature refers to a "warmer" or "redder" light. Interestingly, we perceive high color temperatures as "cool" and low color temperatures as "warm," even though the Kelvin scale actually expresses the opposite. This is because the associations with the colors blue and red are deeply ingrained in our human perception.

Methods for Determining Color Temperature

Color temperature can be measured in various ways. One commonly used method is the use of a colorimeter or spectrometer. This device can measure the spectral power distribution of light and calculate the color temperature from it.
Another approach is to determine the color temperature by comparing it with a reference light, also known as a Planckian radiator. The measured light is compared to the reference light, and the color temperature is determined when both light sources have the same color.

Important Aspects of Color Temperature Measurement

When measuring color temperature, it's important to consider that the actual color of light depends not only on the color temperature but also on the color rendering of the light. Color rendering describes how accurately the light reproduces the colors of an object.

Another important aspect is that color temperature and brightness of the light are not the same. A high color temperature does not necessarily mean that the light is also bright. Similarly, a low color temperature does not necessarily mean that the light is dark.

Impact on Human Perception

Color temperature can have a significant impact on our perception of a scene or object. A high Kelvin value can create a sense of coldness or sterility, while a lower value can convey warmth and coziness. In photography and film production, color temperature is often manipulated to evoke specific moods or emotions.


Effects of Color Temperature on the Psyche

Light and color have always had a strong influence on us as human beings. They can impact our mood and even our physical reactions. But how exactly does light color affect our psyche? In this article, we will explore the influence of light colors on our mood, well-being, and productivity.

Light and Our Circadian Rhythm

The human eye is capable of perceiving a wide range of colors generated by different wavelengths of light. These colors can induce specific physiological reactions and influence our behavior. One of the most well-known applications of this understanding is the use of light therapy to treat seasonal affective disorder (SAD), a type of depression triggered by the changing seasons.

Blue Light

Blue light, which has a high color temperature, is particularly impactful for our body and mind. It is associated with daylight and can help us stay awake and alert. Blue light can inhibit the production of melatonin, a hormone that regulates sleep, thus increasing our vigilance. However, for the same reason, it can also be disruptive if exposed to it shortly before bedtime, as it can lead to sleep disturbances.

Warm Light

On the other end of the spectrum, we find warm, reddish light. This light has a low color temperature and is often associated with relaxation and calmness. It disrupts melatonin production less than blue light and can therefore help prepare us for sleep.

Light Color and Mood

Not only color temperature but also the specific colors of light can influence our mood. Different colors can evoke different emotions. For example, green light is often reported to have a relaxing effect, while red light is often perceived as stimulating.

Appropriate Color Temperature for Different Spaces

Living Room

For living rooms and other relaxation areas, a warmer color temperature (2700K - 3000K) is generally suitable. These warm lights create a cozy and inviting atmosphere that promotes relaxation and comfort.

Kitchen and Bathroom

In kitchens and bathrooms, a slightly higher color temperature (3000K - 3500K) is often recommended. These spaces require clearer lighting for activities such as cooking or grooming.


For workspaces such as offices or workshops, a higher color temperature (4000K - 5000K) is beneficial. These cooler lights promote alertness and concentration.

Outdoor Areas

For outdoor areas such as patios or porches, a higher color temperature (5000K - 6500K) may be suitable to mimic natural daylight.


Understanding Color Temperature in an Industrial Context

In an industrial environment, lighting plays a crucial role in the safety, productivity, and efficiency of employees. Choosing the right color temperature can positively impact the work environment and lead to better outcomes. Let's explore how you can select the appropriate color temperature in an industrial context.

Choosing the Right Color Temperature for Various Industrial Applications

Workshops and Manufacturing Facilities

In workshops and manufacturing facilities where precision work is conducted, it is often beneficial to use a higher color temperature (4000K - 5000K). This cool, bright light enhances visibility and can help minimize errors and improve work quality.

Warehouses and Distribution Centers

In warehouses and distribution centers where employees frequently need to locate and move items, using a medium to high color temperature light (3500K - 5000K) can enhance visibility and efficiency.

Office Spaces

In office environments where employees spend extended periods sitting and staring at computer screens, using a lower color temperature (3000K - 4000K) can help reduce eye strain and create a comfortable work environment.

Physical Fundamentals

In physics, there are terms such as "black body," "black radiator," and "Planck's radiator" that are frequently used to describe various concepts in radiation theory.

What is a Black Body?

A black body is an idealized physical object that perfectly absorbs all electromagnetic radiation incident upon it. It reflects or transmits no radiation. A black body is also an ideal emitter as it emits radiation with a certain intensity dependent on its temperature. The theory of black bodies plays a central role in quantum mechanics and thermodynamics.

Absorption / Emission / Radiation Distribution

A black body fully absorbs electromagnetic radiation regardless of wavelength. This means that no light or radiation is reflected, and all light is absorbed.
A black body emits electromagnetic radiation with a specific intensity depending on its temperature. This emission occurs continuously across a wide spectrum of wavelengths.
The distribution of the emitted radiation of a black body across different wavelengths is described by Planck's radiation law.

Planck's Radiation Law

Planck's radiation law describes the radiation distribution of a black body based on its temperature. It was developed by Max Planck in 1900 and marked the beginning of quantum mechanics. It states that the intensity of radiation decreases with increasing wavelength and increases with increasing temperature. This means that a black body emits more radiation at higher temperatures, and the distribution of radiation peaks shifts toward shorter wavelengths.


Frequently Asked Questions (FAQ)


What is color temperature?

Color temperature is a quantitative method used to describe the color of light and is expressed in the unit Kelvin (K). High color temperatures are associated with "cool" blue tones, while lower color temperatures represent "warmer" red tones.

How is color temperature measured?

Color temperature can be measured using a colorimeter or spectrometer, which measures the spectral power distribution of light. Another method is to compare the light with a reference light and determine the color temperature at which both light sources have the same color.

Why is color temperature important?

Color temperature significantly influences our perception. In photography, film production, and interior design, color temperature is utilized to create specific moods or atmospheres.

What does "black body" mean in physics?

A black body is an ideal object that absorbs all incident radiation and emits radiation with intensity dependent on its temperature.

Why is the concept of the black body important? 

The concept of the black body helps us understand the radiation properties of materials and finds applications in various areas of physics and technology.

What does Planck's radiation law state?

Planck's radiation law describes the distribution of emitted radiation from a black body as a function of its temperature.

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