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Geomagnetic activity in December 1939
Mean Ap11.0No. 662 of 1138
G1+ days5
G3+ days0
Max Ap467 Dec 1939
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 6 Dec 1939 | 5+ | 20 | G1 |
| 7 Dec 1939 | 6o | 46 | G2 |
| 8 Dec 1939 | 5+ | 30 | G1 |
| 16 Dec 1939 | 5- | 10 | G1 |
| 22 Dec 1939 | 5- | 25 | G1 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| December 1938 | 11.4 | 7 | 0 |
| December 1939 | 11.0 | 5 | 0 |
Dates and time slots are UTC. Kp is the 3-hourly planetary geomagnetic index (0–9); Ap is the daily average disturbance. G1–G5 follow the NOAA storm scale (Kp 5- and above counted as G1). Aurora visibility also depends on weather and location. The latest values are preliminary.
About this page
Mean Ap 11.0 in December 1939, No. 662 of 1138 months since 1932; 5 days reached G1 or higher.