HamSandwich

CW is not required. But it helps.

Study › General › G3A › G3A12

G3A12

RADIO WAVE PROPAGATION · - Sunspots and solar radiation; geomagnetic field and stability indices

G3A12G3A →

What does the K-index measure?

  1. AThe relative position of sunspots on the surface of the Sun
  2. BThe short-term stability of Earth's geomagnetic field
  3. CThe short-term stability of the Sun's magnetic field
  4. DThe solar radio flux at Boulder, Colorado
Why The K-index is derived from magnetometer readings taken every three hours and reported on a quasi-logarithmic scale of 0 to 9, so it is a short-term snapshot of how disturbed or stable Earth's geomagnetic field is. Low values (0 to 1) mean a quiet field and good HF conditions, while values of 5 and up indicate a geomagnetic storm with absorption and auroral disruption, especially on high-latitude paths. The A-index is the related daily figure derived from the day's K values.
Watch out The solar flux measured at 2800 MHz is the solar flux index, historically measured at Ottawa and now Penticton, British Columbia (the Boulder, Colorado tie-in is to the NOAA Space Weather Prediction Center, not the flux observatory), and it describes solar activity rather than Earth's magnetic field.
K for Kompass: the K-index watches Earth's magnetic field, updated every 3 hours, 0 = quiet, 9 = storm.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
← G3A11 All of G3A G3A13 →

The rest of G3A

  1. G3A01 How does a higher sunspot number affect HF propagation?
  2. G3A02 What effect does a sudden ionospheric disturbance have on the daytime ionospheric propagation?
  3. G3A03 Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affec…
  4. G3A04 Which of the following are the least reliable bands for long-distance communications during periods of low so…
  5. G3A05 What is the solar flux index?
  6. G3A06 What is a geomagnetic storm?
  7. G3A07 At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight…
  8. G3A08 How can a geomagnetic storm affect HF propagation?
  9. G3A09 How can high geomagnetic activity benefit radio communications?
  10. G3A10 What causes HF propagation conditions to vary periodically in a 26- to 28-day cycle?
  11. G3A11 How long does it take a coronal mass ejection to affect radio propagation on Earth?
  12. G3A12 What does the K-index measure?
  13. G3A13 What does the A-index measure?
  14. G3A14 How is long distance radio communication usually affected by the charged particles that reach Earth from sola…
Yaesu FT-991A HF/VHF/UHF All Mode TransceiverSponsored · View on Amazon →Baofeng UV-5R Dual Band Two Way RadioSponsored · View on Amazon →