#BAFact: Our air is transparent to visible light and radio waves, but absorbs most other kinds of light.* 

We think of Earth's air as being invisible. But it's actually only transparent to visible light - the kind we see with - and radio waves. It absorbs almost every other flavor of light, which is one reason we put observatories on mountain tops, and use balloons and satellites to observe using X-rays, gamma-rays, ultraviolet, and infrared.

More: http://outreach.atnf.csiro.au/education/senior/astrophysics/wavebands.html

Image: DRAO
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But it's actually only transparent to visible light - the kind we see with - is't it the other way around? I was under the assumption that our eyes evolved to see the spectrome of our sun that can reach the surface. 
As Philip's post may go on to say, air isn't always transparent even to visible light. We all know what fog, clouds, and thermal shimmer looks like.
Exactly & that is why our planet is so special for living beings.
...or for these living beings asking the questions. 
a puddle might look at the hole in the ground that it's in. being a perfect fit, the puddle might say that the hole must have been made especially for it. (Douglass Adams)
+Dan Dalessio - that's most of the UV sunlight. Try living in New Zealand or other areas with depleted ozone layer above and you'll get sunburned in half the time,even when it's cloudy. 
Same with gamma and cosmic rays. A small amount of them get through, and there'd be a lot more coming through if we didn't have a magnetic field. But for the most part they're blocked.
At 1,391 ft below sea level is it harder to get a sunburn on the Dead Sea?
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