Current Events

  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
  • Massive Tornado Outbreak on Tornado Alley
    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Io...Read more

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    Massive Tornado Outbreak on Tornado Alley

    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Iowa, Illinois and Missouri. On May 20th, a massive tornado struck Moore, Oklahoma, devastating communities - destroying over 100 homes and hitting two elementary schools and a hospital - with many casualties and deaths. Our thoughts are with our friends and colleagues suffering from these storms. For more on the May 20th storms, see the NOAA Storm Prediction Center Storm Report.
  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.
Various types (frequencies) of radio waves are used for communications.
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Radio Waves

Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than does visible light. We use radio waves extensively for communications.

Radio waves have wavelengths as short as a few millimeters (tenths of inches) and as long as hundreds of kilometers (hundreds of miles). Visible light, for comparison, has wavelengths in the 400 to 700 nanometer range, about 5,000 times shorter than the shortest wavelength radio waves. Radio waves oscillate at frequencies between a few kilohertz (kHz or thousands of hertz) and a few terahertz (THz or 1012 hertz). "Far infrared" radiation borders radio waves on the electromagnetic spectrum; far IR is slightly higher energy and shorter wavelength radiation than radio.

Microwaves, which we use for cooking and for communication, are short wavelength radio waves with wavelengths between a few and a few hundred millimeters (tenths of inches to tens of inches).

Various frequencies of radio waves are used for television and FM and AM radio broadcasts, military communications, mobile phones, ham radio, wireless computer networks, and numerous other communications applications.

Most radio waves pass freely through Earth's atmosphere. However, some frequencies can be reflected or absorbed by the charged particles in the ionosphere.

Last modified July 13, 2005 by Randy Russell.

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