Infrared (IR) light is an invisible form of electromagnetic energy that is naturally radiated by all objects that possess heat. The human body perceives this energy as warmth, distinguishing it from the shorter wavelengths of visible light and ultraviolet (UV) radiation. Seeking natural exposure to infrared light means finding non-artificial sources and methods to absorb this radiant heat energy. This article focuses exclusively on accessing this energy from naturally occurring sources.
Understanding Infrared Light and Natural Sources
Infrared light exists across a spectrum of wavelengths, commonly divided into Near-Infrared (NIR), Mid-Infrared (MIR), and Far-Infrared (FIR). The Sun is the most powerful natural source of IR energy reaching the Earth’s surface. Slightly more than half (approximately 49% to 55%) of the solar radiation that penetrates the atmosphere is infrared energy.
The IR light emitted directly from the Sun is predominantly Near-Infrared, consisting of shorter wavelengths, generally below 4 micrometers. This NIR component penetrates the atmosphere relatively easily and is the primary source of the deep warmth felt from direct sunlight. The Sun’s intense heat, around 5,780 Kelvin, dictates its spectral output, which peaks close to the visible light range but contains a massive volume of invisible IR.
All objects on Earth, including the ground, water, and living organisms, also emit infrared radiation. This terrestrial radiation is primarily in the longer wavelength ranges of Mid-Infrared and Far-Infrared. For instance, objects at typical room temperature radiate energy concentrated mostly in the 8 to 25 micrometer band, which is firmly in the FIR and MIR regions of the spectrum.
Maximizing Infrared Exposure from Sunlight
The most effective way to naturally increase your infrared exposure is through direct sunlight, while simultaneously addressing the risk of harmful UV radiation. The atmosphere acts as a natural filter, and the angle of the sun significantly alters the ratio of IR to UV light reaching the ground.
The optimal times for maximizing the ratio of Near-Infrared to UV light are the early morning immediately after sunrise and the late afternoon before sunset. During these periods, the sun is low on the horizon, forcing its rays to travel through a greater thickness of the Earth’s atmosphere. This increased atmospheric path scatters and absorbs a higher percentage of the shorter-wavelength UV rays, while allowing a greater proportion of the longer-wavelength NIR to pass through.
Exposure during these low-UV periods allows the body to absorb the natural NIR light with a reduced risk of sunburn. The intensity of Near-Infrared can be up to 30% greater in the morning compared to midday sun. Certain clothing materials, such as cotton and polyester, allow a significant amount of Near-Infrared light to penetrate the skin, while dense fabrics like denim or multiple layers can impede this penetration.
Another method of exposure involves seeking out natural thermal mass that has been warmed by the sun. Surfaces such as large stones, concrete, or sand absorb solar energy all day and then naturally re-radiate that heat as Far-Infrared light. Sitting or lying on a sun-warmed rock formation allows the body to absorb this secondary, longer-wavelength FIR energy. This re-radiated heat provides a different spectrum of infrared light than the direct Near-Infrared from the Sun.
Non-Solar Natural Thermal Sources
Beyond direct and re-radiated sunlight, other natural phenomena generate infrared light through thermal processes. Any object or substance that is naturally hot will emit a significant amount of infrared radiation, primarily in the Mid- and Far-Infrared spectrum.
Geothermal activity is a potent natural source of Far-Infrared energy. Hot springs, natural mineral baths, and areas near volcanic vents or geysers feature water and rock heated by the Earth’s internal processes. The inherent heat of these geological structures causes them to continuously radiate Far-Infrared wavelengths, which can be absorbed by the body when in close proximity.
Natural combustion, such as a wood-burning fire, is also an intense source of infrared light. Although a fire produces visible light, it emits far more energy in the form of invisible infrared radiation. Sitting near a natural flame provides a powerful dose of radiant heat, which is a mix of NIR, MIR, and FIR, depending on the temperature of the combustion.
Finally, the Earth itself acts as a massive, low-temperature radiator of Far-Infrared energy. The planet’s surface and atmosphere absorb solar energy and re-emit it, creating a constant, ambient background of FIR radiation.