Condensed (longitudinal):




Define:

The condensed air is the air more packed in and harder for sound to travel through than rarefied air. Condensed air has had many questions follow it, like is it possible to make air so dense that you could see its physical appearance. And the answer that followed was that air is visible, because the sky is the color of the air that the light reflects off of it.


Example: This is an example of dense air, because its so dense its actual visible to the human eye. This might not be the best picture, as a great example but, when air gets dense enough it is more apparent to the human eye.
41394189.ME5J0835_cor_res.jpg



Unlike rarefied, condensed is when.... more compact and easier to see. When light reflects off the condensed air it reflects back, giving the color of the sky, for example.


Sources:

http://van.physics.illinois.edu/qa/listing.php?id=1489