Behaviour of Different Wavelengths of Electromagnetic Light

Behaviour of Different Wavelengths of Electromagnetic Light

Electromagnetic Spectrum and Atmosphere

  • The electromagnetic spectrum is composed of different types of waves each with differing wavelengths and energy levels.
  • The atmosphere interacts with these waves differently, which is fundamental to understanding atmospheric processes.

Ultraviolet Light

  • Ultraviolet (UV) light has shorter wavelengths and is more energetic than visible light.
  • Most UV light is absorbed by ozone molecules in the stratosphere, protecting us from harmful radiation.
  • However, some UV-B reaches the earth’s surface and can cause skin cancer and cataracts in humans.
  • UV-C is the most dangerous but is entirely absorbed in the atmosphere.

Visible Light

  • Visible light is a small, but important, part of the electromagnetic spectrum that our eyes can detect.
  • Visible light passes through the atmosphere to reach the surface, providing the energy needed for photosynthesis.
  • The scattering of visible light by particles in the atmosphere gives us blue skies and red sunsets, a phenomenon known as Rayleigh scattering.

Infrared Radiation

  • Infrared (IR) radiation has longer wavelengths and lower energy than visible light.
  • The atmosphere is semi-transparent to IR, meaning some of it escapes into space, but a significant amount is absorbed and re-emitted by greenhouse gases.
  • This re-emission of IR back to Earth results in the greenhouse effect, which helps to maintain Earth’s temperature.
  • However, excessive absorption and re-emission by increasing greenhouse gases leads to global warming and climate change.

Radio Waves

  • Radio waves have the longest wavelengths and lowest energy of the electromagnetic spectrum.
  • Most radio waves pass freely through the Earth’s atmosphere without any interaction, which is why we can use them for long-distance communication.

Summary

Understanding how different wavelengths of electromagnetic light behave in the atmosphere is key to explain a variety of everyday phenomena, from why the sky is blue to why our planet is warming.