Extremely low frequency (ELF) energy waves travel continuously in this envelope surrounding the earth.

The size and shape of the envelope is always changing due to a number of natural physical phenomena including:
  •    - Amount of solar radiation energy striking the earth's surface - averaging about 1000 watts per square meter.
          (Influenced primarily by the earth's distance from the sun, it's tilt, and albedo)
  •    - Strength of the earth's magnetic field.
          (Determined by it's iron core, rotation and the gravitational influences in our solar system and universe)
  •    - Shape of the earth - about 40,075 kilometers in circumference measured around the equator.
          (Influenced primarily by the position of the moon)
  •    - The constant speed of light - 299,792 kilometers per second.

    Courtesy Link: Stanford University ELF/VLF Research

    Ref: NASA - Earth's Resonance (Schumann) Frequency

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