<p>During a powerful solar flare the amount of x-ray radiation can increase up to 110% in the boundry layer of the atmosphere/space,very little of this will reach the earths surface but it can be measured from high flying planes.</p>

<p>UVC is stopped by the upper layer of the atmosphere so this will never reach the ground,It might be possible to measure some UVC in antarctica because of the ozone hole but it is very weak so one will need special equipment to measure it.</p>

<p>UVB will change very little during a solar flare and only in the shortest wavelenght of the UVB spectrum will additional radiation be measurable.</p>

<p>UVA radiation will not change at ground level.</p>

<p>During a solar flare only the shorter wavelenghts of the electromagnetic spectrum will be affected,hard x-rays the most and the longer wavelenghts will be less affected.</p>

<p>source <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JA011507" rel="noreferrer">https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JA011507</a></p>

<p>source for more detailed information <a href="https://en.wikipedia.org/wiki/Ultraviolet" rel="noreferrer">https://en.wikipedia.org/wiki/Ultraviolet</a></p>

<p><a href="https://i.sstatic.net/xynzd.jpg" rel="noreferrer"><img src="https://i.sstatic.net/xynzd.jpg" alt="enter image description here"></a></p>

<p>i do not have the source for this picture but i think it is free to use.</p>

CC BY-SA 4.0
2020-01-31T08:52:20.307Z
The image appears to be from John Emmert of the Navy Research Lab -- as it's a US govt institution it should be free to use.
MrAzzaman
CC BY-SA 4.0
2020-01-30T18:40:03.837Z
2020-01-30T19:05:28.910Z
2020-01-30T19:05:28.910Z
trond hansen
<p>Solar flares are very variable in size and position. A small one on the edge of the sun's disc would have no effect on Earth, but I presume you mean a large one. UVC would be stopped by the ozone layer, so no increase there. UVB gets through the atmosphere with difficulty, so there might be a small increase there, but nothing to worry about. The atmosphere is completely transparent to UVA, so there could be a significant increase with a very large flare. You wouldn't know this unless you followed the TV weather announcements of ultra-violet hazard. If it happened to be cold and wet in your part of the world it wouldn't affect you unless you were in the habit of sunbathing in single-figure temperatures, lowering cloud and pouring rain. Not many people do this.</p>

<p>More worrying for most people would be the flare's effect on satellites and communications, or even to the electricity grid in the event of a really large coronal mass ejection. The arrival of huge amounts of charged particles emitted by a flare creates electric currents in the atmosphere which in the most severe cases have been known to shut down electricity grids for many hours.</p>

CC BY-SA 4.0
2020-01-30T12:27:35.633Z
The question asks for an extent of increase, so the answer should be at least semi-quantitative, like an order of magnitude (backed with a reference of course, as usual when giving numbers).
Jean-Marie Prival
CC BY-SA 4.0
2020-01-30T14:54:13.797Z
michael i have flagged your answer as very low quality,this is obviously a field you know very little about.please stop spamming our site with low quality answers.
trond hansen
CC BY-SA 4.0
2020-01-30T11:14:58.360Z
2020-01-30T11:14:58.360Z
Michael Walsby
<p>To what extent do the levels of UVA, UVB and UVC radiations on the earth surface increase during <a href="https://en.wikipedia.org/wiki/Solar_flare" rel="noreferrer">solar flares</a>?</p>

CC BY-SA 4.0
2020-01-30T10:10:34.153Z
I know you're asking for the effects on the Earth, but as the source of the radiations is the star, it might be worth asking at the Astronomy SE: https://astronomy.stackexchange.com/
Jean-Marie Prival
CC BY-SA 4.0
2020-01-30T15:10:44.683Z
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JA011507
trond hansen
<sun><uv-light>
To what extent do the levels of UVA, UVB and UVC radiations on the earth surface increase during solar flares?
Franck Dernoncourt
# To what extent do the levels of UVA, UVB and UVC radiations on the earth surface increase during solar flares?

(Asked by: username_0 on 2020-01-30)

To what extent do the levels of UVA, UVB and UVC radiations on the earth surface increase during [solar flares](https://en.wikipedia.org/wiki/Solar_flare)?

**Tags:** sun, uv-light

> **Comments:**
> **username_1**: I know you're asking for the effects on the Earth, but as the source of the radiations is the star, it might be worth asking at the Astronomy SE: https://astronomy.stackexchange.com/  
> **username_2**: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JA011507  

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## 2 answers

### Answer by username_2 on 2020-01-30. Score: 9

During a powerful solar flare the amount of x-ray radiation can increase up to 110% in the boundry layer of the atmosphere/space,very little of this will reach the earths surface but it can be measured from high flying planes.

UVC is stopped by the upper layer of the atmosphere so this will never reach the ground,It might be possible to measure some UVC in antarctica because of the ozone hole but it is very weak so one will need special equipment to measure it.

UVB will change very little during a solar flare and only in the shortest wavelenght of the UVB spectrum will additional radiation be measurable.

UVA radiation will not change at ground level.

During a solar flare only the shorter wavelenghts of the electromagnetic spectrum will be affected,hard x-rays the most and the longer wavelenghts will be less affected.

source <https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JA011507>

source for more detailed information <https://en.wikipedia.org/wiki/Ultraviolet>

[![enter image description here](https://i.sstatic.net/xynzd.jpg)](https://i.sstatic.net/xynzd.jpg)

i do not have the source for this picture but i think it is free to use.

> **Comments:**
> **username_3**: The image appears to be from John Emmert of the Navy Research Lab -- as it's a US govt institution it should be free to use.  

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### Answer by username_4 on 2020-01-30. Score: -4

Solar flares are very variable in size and position. A small one on the edge of the sun's disc would have no effect on Earth, but I presume you mean a large one. UVC would be stopped by the ozone layer, so no increase there. UVB gets through the atmosphere with difficulty, so there might be a small increase there, but nothing to worry about. The atmosphere is completely transparent to UVA, so there could be a significant increase with a very large flare. You wouldn't know this unless you followed the TV weather announcements of ultra-violet hazard. If it happened to be cold and wet in your part of the world it wouldn't affect you unless you were in the habit of sunbathing in single-figure temperatures, lowering cloud and pouring rain. Not many people do this.

More worrying for most people would be the flare's effect on satellites and communications, or even to the electricity grid in the event of a really large coronal mass ejection. The arrival of huge amounts of charged particles emitted by a flare creates electric currents in the atmosphere which in the most severe cases have been known to shut down electricity grids for many hours.

> **Comments:**
> **username_1**: The question asks for an extent of increase, so the answer should be at least semi-quantitative, like an order of magnitude (backed with a reference of course, as usual when giving numbers).  
> **username_2**: username_4 i have flagged your answer as very low quality,this is obviously a field you know very little about.please stop spamming our site with low quality answers.  

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