[wxqc] Mammatus sans Thunderhead

[Victor Engel]

I have more pictures of the event on my weatherunderground blog at
http://www.wunderground.com/blog/Brillig/show.html including a comment from
a photographer I know that he thinks its a gravity wave. I'm skeptical, but
I don't know much about gravity waves. Care to comment further? Since this
is probably off-topic for this group, feel fee to post any discussion to my
blog instead.

On 10/30/06, Evan Bookbinder <Evan.Bookbinder at noaa.gov> wrote:
>
>  Mammatus form when precpitating ice particles falling from a thunderstorm
> anvil or dense high cloud cover sublimate due to very dry air below the cloud
> base. The sublimation process causes the air to cool and clouds to descend
> as mammatus. Because they need to have very dry air below cloud base, they
> are seen more often in the Plains & western US where dry mid level air is
> advected from the southwest Deserts across the Rockies, and are not as
> common where the air mass is more humid.
>
> Evan
>  ------------------------------
> *From:* wxqc-bounces at lists.gladstonefamily.net [mailto:
> wxqc-bounces at lists.gladstonefamily.net] *On Behalf Of *Victor Engel
> *Sent:* Monday, October 30, 2006 11:03 PM
> *To:* Discussion of weather data quality issues
> *Subject:* [wxqc] Mammatus sans Thunderhead
>
> My weatherbook states that mammatus clouds are associated with anvil
> clouds. Today, however, there were mammatus clouds that apparently were
> caused simply by upper-level winds.
>
> I noticed the clouds forming in the west as I drove home for my lunch
> break. I climbed on the roof of my house when I got home and took about 100
> pictures, which will be processed when I have time. After about an hour, the
> whole system had mostly overpassed me to the east. It was  a very
> fast-moving system with no associated rain as far as I could tell. Another
> hour later, the sky was virtually cloud free, although those that remained
> had interesting patterns. Jets flying overhead left no contrails. One photo,
> at least, is ready for viewing.
>
> http://www.pbase.com/victorengel/image/69433594/original.jpg
>
> I posted this to weather matrix, but have yet to receive a response. If
> any of you know more specifically what I observed, I would really be
> interested to hear what you have to say.
>
> This was noon today in Austin, Texas.
>
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