This is so cool...a roll cloud

[Tripper11]

Explanation: What kind of cloud is this? A roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form. Roll clouds may actually have air circulating along the long horizontal axis of the cloud. A roll cloud is not thought to be able to morph into a tornado. Unlike a similar shelf cloud, a roll cloud, a type of Arcus cloud, is completely detached from their parent cumulonimbus cloud. Pictured above, a roll cloud extends far into the distance in 2009 January above Las Olas Beach in Maldonado, Uruguay.

from http://antwrp.gsfc.nasa.gov/apod/archivepix.html">Astronomy Picture of the Day

[Redstone]

1. It doesn't GET much cooler than that, indeed.

Redstone

[Forkboy]

2. That's an awesome pic!

I've never seen one that well defined and large.

[stuntcat]

3. mighty cool!

love it!

[GoCubsGo]

4. That IS cool!

Thanks for sharing it!

[CaliforniaPeggy]

5. I have NEVER seen one of those before!

Thank you for showing this great pic!

[AsahinaKimi]

6. I found some more images..

They are spectacular, thanks!

[Tripper11]

8. Thanks AsahinaKimi...very nice addidtions!

I'd never seen anything like this before.
Would sure love to see one for real.
Maybe one day.

[MicaelS]

9. Great pictures, thanks...

The first one over the city at that angle looks ominous for some reason.

[graywarrior]

7. Love it!

[Capn Sunshine]

10. That is so obviously a disguised UFO

how dumb do these aliens think we are?

[jobycom]

11. No kidding, and that lame MIB explanation doesn't fool anyone, either!

Cold fronts? Come on, that's worse than swamp gas!

[lizziegrace]

12. My nephew's a storm chaser

here's a shot he got in Oklahoma.

[Iggo]

13. If I saw that in real life, I'd have to change my shorts. (n/t)

[denbot]

14. Alley and I saw one on Anacapa Island a year ago last October.

We knew a big low system was headed south from the Bearing Sea. We had reservations for some time so we went for it. We had just enough time to hike all our gear to the campground and set up when we saw this massive cloud/wave heading at us from the "wrong" direction (south). The really freaky thing was that the wind changed direction and headed towards the approching storm just before the shite hit the fan.

We spent the next two days in our tent. but got two great days of kayaking and snorkeling after that.

I was too flabbergasted to take a picture of it, but here is the rainbow two days later



Paddling through one of Anacapa's many sea caves.