A Why people say we can't "feel" UV?

[jaumzaum]

I was taught that the only radiation that we can properly "feel" is infrared, while UV is not properly absorbed by the molecules of our body in the form of thermal energy.
But then I I saw the following picture which shows the water absorption spectrum:

We can clearly see there that the UV radiation is indeed greatly absorbed by water molecules, so what is the correct explanation for these? Can UV really heat our bodies greatly than IR? Was I taught wrong? I could have some explanation to that, but I'm not sure if they make sense:
We know our bodies are composed mainly by water, but the radiation gets first to the skin, which contains some pigments, such as melonin. It is possible that some of the molecules in the skin act first as a barrier that blocks the UV radiation from reaching the water molecules.
Also, we know the majority of high frequency radiation is blocked by our atmosphere, such as the picture (the blue line is radiation in the Eath surfface) below:

Radiation with a wavelength smaller than 300nm is almost not absorbed, so it does not get to our bodies, and so we can't feel it.
But what if it got here in the same intensity as IR does, what would happen? Would we feel it as heat or we would feel nothing and just develop some cancer in a few days after that?

 

[anuttarasammyak]

We feel UV by suntan.

 

[phinds]

We feel UV by suntan.

That's not feeling it, that's just the result of it. Not the same thing at all.

 

[tech99]

Of course, all types of radiation can cause heating if they are absorbed by the skin or anything on its surface such as water or oil. I felt sure I could feel warmth from X-rays during a CT scan.
By the way, there is a lot of interest at the moment in UVB effects on skin, because of the production of Vitamin D. This is very important in COVID 19, as deficiency of Vitamin D is widespread and undermines the body's resistance to respiratory infection. It seems uncertain if the chemical reaction occurs in oil on the surface, in the outer Epidermis or in the lower Dermis

 

[sophiecentaur]

I was taught that the only radiation that we can properly "feel" is infrared, while UV is not properly absorbed by the molecules of our body in the form of thermal energy.

If we were subject to the level of Power Flux of UV that we get from the IR part of the solar spectrum we would be dead! The atmosphere screens us from a lot of solar UV and, of course, any naturally occurring situation with high levels of UV has loads more incident IR power so how would you identify the 'feel' of the incident UV contribution?

What is meant by "properly absorbed"? The UV energy gets into the skin and damages DNA as well as causing a rise in temperature. A tiny bit of chemical potential energy, due to cell damage, is hardly relevant in the bigger picture of the heating effect.

I felt sure I could feel warmth from X-rays during a CT scan.

There would be other sources of power in the scanner - warm air from the system was probably what you felt. A Sievert is a measure of the energy of an Xray dose and it's 1J/kg. A CT scan uses less than 10mSv - 'nuff said?

 

[A.T.]

I felt sure I could feel warmth from X-rays during a CT scan.

If you could, you would not be here to tell the story.

 

[sophiecentaur]

If you could, you would not be here to tell the story.

During my Radiotherapy sessions I kept feeling warm and cold drafts (of air) over my body, under that awful cotton gown. In an MI scan, the background noise was by far the dominant sensation.