Shortwave radiation

Shortwave radiation (SW) is radiant energy with wavelengths in the visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra.

There is no standard cut-off for the near-infrared range; therefore, the shortwave radiation range is also variously defined. It may be broadly defined to include all radiation with a wavelength between 0.1μm and 5.0μm or narrowly defined so as to include only radiation between 0.2μm and 3.0μm.

There is little radiation flux (in terms of W/m²) to the Earth's surface below 0.2μm or above 3.0μm, although photon flux remains significant as far as 6.0μm, compared to shorter wavelength fluxes. UV-C radiation spans from 0.1μm to .28μm, UV-B from 0.28μm to 0.315μm, UV-A from 0.315μm to 0.4μm, the visible spectrum from 0.4μm to 0.7μm, and NIR arguably from 0.7μm to 5.0μm, beyond which the infrared is thermal.^[1]

Shortwave radiation is distinguished from longwave radiation. Downward shortwave radiation is sensitive to solar zenith angle, cloud cover and surface albedo.^[2]

See also

• Outgoing longwave radiation

External links

• National Science Digital Library - Shortwave radiation
• Measuring Solar Radiation: The Solar Infrared Radiation Station (SIRS). A lesson plan that deals with shortwave radiation from the SIRS instrument.

Notes

1. However, the definition of thermal infrared may start at wavelengths as short as 1.1μm (longer than which optical instruments have difficulty measuring) or anywhere between 2.0μm and 4.0μm, depending on the method of measurement and its purpose.
2. L. Chen, G. Yan, T. Wang, H. Ren, J. Calbó, J. Zhao, R. McKenzie (2012), Estimation of surface shortwave radiation components under all sky conditions: Modeling and sensitivity analysis, Remote Sensing of Environment, 123: 457–469.

References

• Zhang, Y., W. B. Rossow, A. A. Lacis, V. Oinas and M. I. Mischenko (2004). "Calculation of radiative fluxes from the surface to top of atmosphere based on ISCCP and other global data sets: Refinements of the radiative transfer model and the input data." Journal of Geophysical Research-Atmospheres 109(D19105).
• L. Chen, G. Yan, T. Wang, H. Ren, J. Calbó, J. Zhao, R. McKenzie (2012), Estimation of surface shortwave radiation components under all sky conditions: Modeling and sensitivity analysis, Remote Sensing of Environment, 123: 457–469.