Tuesday, September 22, 2015

Fata Morgana

Polar regions can produce some interesting optical effects due to extreme temperatures and/or low sun angles. Yesterday was beautifully calm at Zodiac Camp and an inversion formed (i.e. when air closer to the surface is colder than the air above it - normally air temperatures decrease with altitude). The colder, denser air near the surface has a higher refractive index compared to the warmer (though still cold) and less dense air above it. The difference in refractive index acts like a lens, bending light.

Yesterday's inversion produced a Fata Morgana; a phenomenon where, to the observer, an image of the underlying surface is mirrored in the air above it. Often it looks like the horizon line is stretched.

The Fata Morgana can be seen as a white bar (probably as a result of the underling snow  and sea ice) on the horizon. The blue line give a partial outline of the faintly visible Royal Society Range of mountain.


At September 22, 2015 at 9:55 PM , Blogger Jim said...

Never heard of this -- pretty cool!


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