Origins and Roles of UV and IR

Origins of Ultraviolet (UV) and Infrared (IR) Radiations

UV and IR are parts of the electromagnetic spectrum, which originates from the Sun.
Ultraviolet (UV) radiation has a wavelength shorter than light visible to humans but longer than X-rays. It carries more energy than visible light and can ionise atoms.
Infrared (IR) radiation falls in the section of the electromagnetic spectrum just beyond red light, and has longer wavelengths than visible light but is less energetic.
The Sun produces a continuous spectrum of electromagnetic radiation, from X-rays to radio waves; UV and IR lie within this radiant energy from the Sun.

Roles of UV in the Atmosphere

UV radiation plays a key role in the creation of the Earth’s ozone layer, where UV-C radiation dissociates oxygen molecules, the single oxygen atoms can then combine with more oxygen to create ozone.
UV-B radiation is absorbed by this ozone layer, protecting Earth from harmful levels of UV.
However, excessive UV-B also harms organisms, by damaging proteins and DNA in skin cells, which can lead to skin cancer in humans. -UV-A whilst less energy intensive, causes aging of the skin and can trigger an indirect damage to the cells’ DNA.

Roles of IR in the Atmosphere

IR radiation is primarily involved in heat transfer across the Earth’s atmosphere, contributing to the greenhouse effect.
The energy of incoming sunlight is absorbed by the Earth’s surface and then emitted as infrared radiation.
Certain greenhouse gases like water vapour, carbon dioxide, and methane, absorb this IR radiation, trapping heat in the atmosphere.
IR radiation influences the Earth’s temperature and helps in maintaining the life supporting temperature range on Earth.

Detection and Measurement of UV and IR

UV radiation is measured by spectroradiometers, or simple broadband sensors, and can be observed using UV sensing beads that change colour.
IR radiation can be detected using thermopile, bolometer, pyroelectric detectors, or other advanced sensors.
Both are critical measurements in numerous scientific studies, including atmospheric science, climatology, and environmental science.