Dusty parhelia

No, that’s not a baseball player that played for the Dodgers or Giants back in the 1950s, that was Dusty Roads; though Dusty Parhelia would be a nice name for a baseball player.  Yesterday, with our slightly dusty skies, and on the 22 degree halo ring, and horizontally from the sun’s position, was a couple of sun dogs (parhelia) late in the day associated with those cirriform clouds we had.   You know by now that those high clouds are comprised of small ice crystals.  Here’s a few shots of those clouds, which were often CIrrostratus with embedded other Cirrus cloud species like spissatus, fibratus, and uncinus.

CIrrostratus fibratus with a faint 22 degree halo.
The denser portions tend toward Cirrus spissatus, but several other species are also present.
Faint sun dogs or parhelia located horizontally from the sun on the fainter halo
The ice crystals in those clouds are typically hexagonal (six-sided) plates, ones that fall face down.  If you could be there in them, and see them falling, at eye level you would see only the sliver side of them, but if you looked down at one that went by, you would see the whole hexagonal plate.  The way that they fall is why aircraft laser imagery, when the laser is oriented in the vertical, captures such beautiful, full images of plates and other flat crystals in ice clouds as the aircraft flies through them.

The sun’s white light is separated into its colored components in these hexagonal crystals (but only at certain specific angles) and for this reason, the bright spots are at the same locations relative to the sun.  Since I am not an atmo optician, I am relying on the links above to provide  more complete, comprehensible explanations.

Note: Caption function stopped working again in WP for the fourth photo, and after half a dozen tries, will write it here:

Photo 4 caption:  An especially vivid parhelia can be seen just above the horizon at lower left.  The brightest ones like this are usually associated with aircraft contrails since those have high concentrations of pristine crystals. A flying saucer, or a bird with its wings closed at the instant the photo was taken, is also visible.

Continuing….

Sat image loop from the U of WA weatherfolk show lots more cirriform clouds in route to AZ next few days with occasional breaks.  So, keep your camera ready for optics and sunrise/sunset color.

The weather ahead?  Dusty cold snap.

“Dusty” is kind of the word of the day today.

Long foretold big Cal storm on the 12th-13th affects southeast AZ mostly with wind and dust on the 13-14th followed by unusually cool weather for mid-April.  A hint of rain excitement for Catalinians has begun to show up in model runs, such as this one from the U of WA for early Saturday morning on the 14th.  Yay.

The End

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.