Classification of X-ray Solar Flares
or "Solar Flare Alphabet Soup"
solar flare is an explosion on the Sun that happens when energy
stored in twisted magnetic fields (usually above sunspots) is
suddenly released. Flares produce a burst of radiation across
the electromagnetic spectrum, from radio waves to x-rays and gamma-rays.
classify solar flares according to their x-ray brightness in the
wavelength range 1 to 8 Angstroms. There are 3 categories: X-class
flares are big; they are major events that can trigger planet-wide
radio blackouts and long-lasting radiation storms. M-class
flares are medium-sized; they can cause brief radio blackouts
that affect Earth's polar regions. Minor radiation storms sometimes
follow an M-class flare. Compared to X- and M-class events, C-class
flares are small with few noticeable consequences here on
figure shows a series of solar flares detected by NOAA satellites
in July 2000:
category for x-ray flares has nine subdivisions ranging from,
e.g., C1 to C9, M1 to M9, and X1 to X9. It's a logartithmic scale. M1 is 10 times stronger than C1. X1 is 10 times stronger than M1, and so on.
In the figure,
above, the three indicated flares registered (from left to right) X2,
M5, and X6. The X6 flare triggered a radiation storm around Earth
nicknamed the Bastille
Peak (W/m2)between 1 and 8 Angstroms
< = I < 10-5
< = I < 10-4
> = 10-4
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