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Naturally occurring ELF waves are present on Earth, resonating in the region between ionosphere dan surface. They are initiated by lightning strikes that make electrons in the atmosphere oscillate. Though VLF signals were predominantly generated from lightning discharges, it was found that an observable ELF component (slow tail) followed the VLF component in almost all cases. The fundamental mode of the Earth-ionosphere cavity has the wavelength equal to the circumference of the Earth, which gives a resonance frequency of 7.8 Hz. Frekuensi ini, dan mod resonans lebih tinggi iaitu 14, 20, 26 dan 32 Hz appear as peaks in the ELF spectrum dan dinamai resonans Schumann.

They have also been tentatively identified on Saturn's moon Titan. Titan's surface is thought to be a poor reflector of ELF waves, so the waves may instead be reflecting off the liquid-ice boundary of a subsurface ocean of water dan ammonia, the existence of which is predicted by some theoretical models. Titan's ionosphere is also more complex than Earth's, with the main ionosphere at an altitude of  but with an additional layer of charged particles at . This splits Titan's atmosphere to some extent  into two separate resonating chambers. The source of natural ELF waves on Titan is unclear as there doesn't appear to be extensive lightning activity.

Finally, huge ELF radiation power outputs of 100,000 times the Sun's output in visible light may be radiated by magnetars. The pulsar in the Crab nebula radiates powers of this order at the frequency 30 hertz . Radiation of this frequency is below the frekuensi plasma of the interstellar medium, thus this medium is opaque to it, dan tidak boleh dilihat dari Bumi.