If Solar Flares are classed A, B, C, M X, what would be the class of normal sunlight

[Michael Erlewine]

If Solar Flares  are classed A, B, C, M X, what would be the class of normal sunlight. Looking at the graph, I suppose normal sunlight would be like C.0 Class. Is this true?

 

Another question: When there is almost no activity and the graph drops down to Class B or Class A, what is going on to cause this? Using the familiar SolarHam.com display with some callouts.

Edited March 29 by Michael Erlewine

[Marcel de Bont]

Solar flares are the prime source of X-rays and just sunlight itself consist of very very little X-rays if I remember correctly, I do not think they could even be measured by satellites as active regions/solar activity would drown out X-rays from pure sunlight and the corona at all times. Someone else might have a better answer but I think this is the case.

The drops to the B or even A class are caused by the Earth coming in between the Sun and the satellite during the equinoxes so once a day you will have a drop in the data as there is no Sun visible for the satellite.

[Drax Spacex]

There will always be some X-Ray Flux even with no flares or active regions on the visible disk - which on average depends on where we are in the solar cycle.

The table found here provides the conversion between flare class and X-Ray Flux in W/m^2  https://www.spaceweatherlive.com/en/help/what-are-solar-flares.html

And here's related topic - two years into Solar Cycle 25 - on a day when the Sun was very quiet.  

 

[helios]

On 3/29/2023 at 2:42 PM, Michael Erlewine said:

If Solar Flares  are classed A, B, C, M X, what would be the class of normal sunlight.

Maybe it's a misunderstanding, but for completeness: Those are flares in the x-ray spectrum. They have little to nothing to do with what we perceive as "sunlight" in the visible spectrum.
During solar minimum, the x-ray background can go below A1-level. Which is a 100 times smaller flux than the current C1-level.