Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

RF emitted from Lightning strikes

  1. Jan 27, 2007 #1
    Hello All,

    I’m still perusing the whole idea of tapping into the energy in the Schumann Resonance cavity. But, even if I can manage to do that, I figured it would be a good idea to at least find out how much energy is actually there to couple with.

    Recently, I corresponded with a researcher who actually studies the subject (frequencies in the ELF/VLF range) and asked him how much energy is actually stored in the cavity at the fundamental frequency of 7.83Hz. He said that there is only about 1 joule of energy constantly circulating at any one time because, though the cavity is stimulated by some 100 lightning strikes per second, most of the energy is converted to heat. The remaining RF energies are actually in the low to mid kHz spectrum. So I believe that the most powerful RF energy has to be collected in the kHz range and not the Hz range.

    I was just wondering if anyone here knows what frequency, in the kHz, band(s) contains the most RF energy from lightning strikes?

    Jason O
  2. jcsd
  3. Jan 27, 2007 #2
    Basically a lightning strike is a pulse of electrical energy, which according to fourier analysis is the sum of infinite frequencies from 0 Hz to Gamma radiation, but mostly some frequencies are attenuated more than others.

    I don't know where the peak is, most likely in the UV (ultraviolet) because lighting is whitish blue a tail of UV.

    1 Joule total energy from Schuman resonances is hardly enough anyway, you could possibly recover a pico or a femto joule.

    There is vasts amounts of energy in the atmosphere waiting to be tapped, glad somebody is working on that, that was Tesla's dream, and he may actually taped some energy from the atmosphere using his tesla coils. Suggest you read more about that.
  4. Jan 27, 2007 #3


    User Avatar
    Science Advisor
    Gold Member

    Humm. IMHO you would be better off with something with a little more energy gain; like ocean waves, wind, solar. How about nuclear?
  5. Jan 27, 2007 #4
    Hi Waht,

    Actually I have done a lot of reading up on Tesla as well as research into many of the things he worked on (Radiant Energy, one-wire power systems, Tesla Coils etc.) Here is an approch that I want to use to tap into the ambiant energy as soon as I can figure out how to do it practicaly:


    - Jason O
  6. Jan 28, 2007 #5
    Assuming you have access to a library that can order standards try to get a copy of "STANAG 4236" this is the NATO standard for lightning, and gives statistical data on all aspects of lightning including the RF spectrum. I've never seen a free source for STANAGs though.

    I will try and remember took look at my copy on Monday morning and give you an indication of the peak frequency.
  7. Jan 28, 2007 #6
    Hi Panda,

    Thanks, that would help me greatly :-).

    - Jason O
  8. Jan 29, 2007 #7
    OK - these figures are taken off a graph so they are visual estimates rather than definate values.

    the EM Field you would expect to detect at ground level 1.5-2km from the strike can be divided into two linear sections.

    Section 1 drops at 20dB/decade to 100MHz
    Section 2 drops at 45dB/decade above 100MHz

    at 200 kHz
    Voltage is around 100 dB uV/m measured at 1kHz interval
    Current is around 69dB uA/m measured at 1kHz interval

    Therefore you would need to balance achievable recieving antenna gain thats going to drop off with reducing frequency with spectral power which drops off with increasing frequency.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: RF emitted from Lightning strikes