Plain-language answer: The K index summarizes geomagnetic disturbance over a three-hour interval at a specific observatory on a quasi-logarithmic scale from 0 to 9.
Why it matters
Planetary Kp combines observations into a broader index, while local K can differ by latitude and station. Higher values often disrupt high-latitude HF paths and support auroral activity.
Use it correctly
Check whether the report is local K or planetary Kp, note the time interval, and compare it with the exact path and latitude.
The common mistake
Calling K a real-time global measurement that affects every path equally.
Decision boundary
Current regulation, program rules, manufacturer limits, exact station configuration, and live observations control. Recheck changing rules, solar conditions, and operating status before acting.
