While the electromagnetic spectrum of "light" includes everything from gamma rays to x-rays and radio waves, the three bands of light energy most beneficial to plant, animal, and human health and life are Ultraviolet (UV) light, Visible Light, and Infrared (IR) light. Let's learn more about each of these three bands of light and the purpose of each!
Ultraviolet Light (200nm-400nm)
We start with Ultraviolet (UV) Light, the invisible light energy directly to the left, or below, blue/violet visible light (hence the name, ultra-violet).
UV light is invisible because it is too short a wavelength to be detected by the human eye. Though it's invisible to us, UV light still profoundly affects life and is best known for its ability to cause skin tanning by its interaction with the melanin in our skin, as well as its responsibility in the production of Vitamin D.
UV light can be broken down into three segments, UV-A, UV-B, and UV-C light.
UVA light (315-400nm) is closest to violet visible light, and actually overlaps a bit into the visible spectrum. Blacklights are UVA lights.
UVB light (280-315nm) is next, and best known for its interaction with our skin and the production of Vitamin D.
UVC light (200-280nm) is last, the band of UV light farthest from visible light. It is best known for its germicidal abilities (ability to kill bacteria and disinfect), and most UVC is absorbed by the atmosphere (so doesn't reach Earth's surface).
Visible light (380-700nm)
Moving up the spectrum, we have the visible light spectrum! Visible light contains the rainbow of colors - Red, Orange, Yellow, Green, Blue, and Violet - all of which together comprise white light.
The human eye has photoreceptors (cones) that enable us to detect these bands of color, of which we are most sensitive to the wavelengths right in the middle of the visible spectrum, around 555nm. Our eyes are least sensitive to red and blue, colors that create a vivid environment. Using a special neodymium glass light bulb like Chromalux® helps by absorbing some of the heightened yellow/green spectrum, in turn increasing our ability to see all colors more vividly!
Infrared light (700nm-1nm)
Next is infrared light, another band of light energy invisible to the human eye, following the visible red color wavelengths.
Infrared light is essentially thermal energy or heat, used in many applications such as night vision goggles and thermal imaging cameras. Infrared light is incredibly nourishing; red and near-infrared light (the infrared band closest to visible red light) are the only wavelengths of light able to penetrate the skin, promoting cell regeneration, tissue oxygenation, and overall health and energy in the cells.
And those, in a nutshell, are the three spectrums of light! These bands of energy are all present in natural sunlight, so next, let's explore the meaning of what is full spectrum lighting as it relates to Light bulbs and so-called "artificial" lighting!