[paulh]

Cold front on the way...

[reeftool]

I caught this sundog today near Lake George, NY.

[rycheme]

[paulh]

[RichardS]

rycheme

Great colours! What causes this phenomenon?

Richard.

[rycheme]

Great colours! What causes this phenomenon?

Richard.

TBH, I have no idea!

[RichardS]

TBH, I have no idea!

If we wait a bit, maybe Douglas_of_Sweden will see this and explain. I think he knows about this sort of stuff

Richard.

[Sagitta]

(last one is cheating since it wasn't taken with the Pentax! :P )

[Sagitta]

All double-posting up in here (because I didn't realize we weren't limited to just rainbows).

Last summer we had a storm roll in just as we were headed into Sam's Club to do some shopping.



By the time we left and drove the half hour home, the sky had turned blood red. This second shot is SOOC and was rendered pretty darn accurately by the Pentax sensor.

[paulh]

A late January storm passing thru...(xposted from POTW thread)

[paulh]

Some strange but nice wispy clouds at sunset recently -
K10D, 18-55 kit lens

[ErZi]

One from last spring.

[ErZi]

Rainbow at sunset.

[Douglas_of_Sweden]

If we wait a bit, maybe Douglas_of_Sweden will see this and explain. I think he knows about this sort of stuff

Richard.

Sorry for my slow response. Have been working too much this winter and not had time for the forum.
What you have in that excellent shot is a deck of cirrus clouds, that means ice chrystal clouds at a height of about 10km. The pattern is caused by gravity waves in the atmosphere. Such waves are common and often leave no trace that we can see without sophisticated instruments. However, sometimes a cloud is so close to forming chrystals (or droplets) that the vertical motion caused by the waves are enough to form and evaporate the clouds in the upward and downward parts of the wave, respectively. There can be gravity waves of different wavelenght, or even different directions present at the same time. It looks like you have that in part of the image, which cause the criss-cross pattern as the waves cross each other and superimpose. Sometimes you can observe the corresponding behavior on small water surface waves when waves from different sources meet. The gravity waves are typically created by for example fronts, high storm clouds, air flow over mountains etc.

[Douglas_of_Sweden]

Some strange but nice wispy clouds at sunset recently -
K10D, 18-55 kit lens

This is again cirrus clouds, but here they have been caught up in the jet wind. The jet wind is a section with very high wind speed that moves above the warm and cold fronts just below the tropopause at a height of 10-15km. Because a worm front is tilting forward (as warm light air slides up on top of cold heavy air) it means that the jet wind will pass in front of the warm front. It is therefore usually said that these sort of clouds is warning for a weather change, as the front will soon pass as well. In Swedish we call these clouds "skidspetsar" meaning "ski tips" (not sure if I got that right...you know the front end of traditional skis which are bent upward), both because of the shape and because they in the winter is warning for snow fall.