Daylight and artificial light sources differ in their wavelength distribution, which affects the color temperature and overall quality of the light. Here are the main differences between daylight and artificial light:
Color Temperature: Color temperature is a metric used to describe the color appearance of light sources. It is measured in Kelvin (K). Daylight typically has a higher color temperature, ranging from about 5,000 K to 6,500 K, which is considered "cool" or bluish-white. Artificial light sources, depending on the type, can have a lower color temperature, often ranging from 2,000 K to 5,000 K, resulting in "warm" or yellowish-white light.
Spectral Distribution: Daylight, particularly natural sunlight, provides a continuous spectrum of light that spans the entire visible spectrum. It contains all the colors of the rainbow and has a relatively smooth distribution across different wavelengths. Artificial light sources, on the other hand, often emit light in a more limited range of wavelengths. For example, fluorescent lights have discrete emission lines, while LED lights can be designed to mimic a broader spectrum.
Ultraviolet Content: Daylight contains ultraviolet (UV) radiation, particularly in the UV-A and UV-B regions, which are responsible for effects like tanning, vitamin D synthesis, and potential sunburn. Artificial light sources generally do not emit significant amounts of UV radiation, unless they are specifically designed for certain applications like UV sterilization or phototherapy.
Variability: Daylight changes throughout the day due to the position of the sun and atmospheric conditions. The color temperature and spectral distribution of daylight can vary based on factors such as time of day, geographical location, weather conditions, and season. Artificial light, on the other hand, can be designed to have a consistent and predictable spectral distribution, providing a stable light source.
It's important to note that artificial light sources have evolved to better replicate the properties of natural daylight. Some advanced artificial lighting technologies, such as full-spectrum LEDs or daylight-mimicking bulbs, aim to provide a more balanced and natural light spectrum. These advancements allow for better color rendering, visual comfort, and the ability to support activities that benefit from specific qualities of daylight.