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Posted at 11:00 AM ET, 07/26/2008

Photography: Thunderstorm Cloud Tops

By Kevin Ambrose

The sun is setting behind the anvil top of cumulonimbus clouds last Sunday evening. This photo was taken from Laurel, Md..

Last Sunday evening, I was leaving a swim meet in Laurel, Md. and I noticed towering thunderstorm clouds on the western horizon. Rays of sunlight and shadows appeared above the storm as the its anvil-shaped cloud top partially blocked out the sunlight. These rays of sunlight that stream through (and around) clouds are called "crespicular rays."

Keep reading for a photo close-up of the storm's cloud top and an explanation why it's often anvil shaped. See our full forecast for the outlook through early next week.

The sun emerges from behind the anvil top of cumulonimbus clouds Sunday evening. This photo was taken from Laurel, Md.

Well-developed thunderstorm clouds (cumulonimbus clouds) are often characterized by a flat, anvil-like top caused by straight line winds at the higher altitudes which shear off the top of the cloud, as well as by an inversion over the thunderstorm caused by rising temperatures above the tropopause, the atmospheric layer between the troposphere (the lowest layer) and the stratosphere. This anvil shape resembles a mushroom top and can precede the main cloud structure for many miles.

By Kevin Ambrose  | July 26, 2008; 11:00 AM ET
Categories:  Thunderstorms  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Late Storms to Become the Norm
Next: Update: Isolated Storms Popping Up


Kevin, I realize this may be a bit early, but when will your calendars for next year be available?

Posted by: ~sg | July 26, 2008 11:32 AM | Report abuse

Isn't "crepuscular rays" the correct spelling???

Posted by: El Bombo | July 26, 2008 11:57 AM | Report abuse

One further question: Aren't the towering mushroom clouds associated with nuclear and thermonuclear explosions classified as artificially-induced cumulonimbus clouds, similar to the pyrocumulus associated with large forest fires?

It would be interesting to find out from the NRC or Energy Department if lightning has ever been observed emanating from a nuclear-induced mushroom cloud. Lightning strikes are a common feature with the massive plumes resulting from volcanic eruptions. These plumes often rise into the stratosphere [and the dust cools global temperatures for a time following a massive eruption].

Posted by: El Bombo | July 26, 2008 12:11 PM | Report abuse

Gorgeous shot!!

Posted by: WeatherGang fan | July 26, 2008 1:58 PM | Report abuse

sg, I have not planned the calendars yet, I guess I should start soon.

El Bombo, I've seen it spelled both ways. Your way may be the correct spelling.

Posted by: Kevin, Capital Weather Gang | July 26, 2008 2:33 PM | Report abuse

I wish you guys would let people post their own storm photos like you did before.

Posted by: Anonymous | July 26, 2008 3:12 PM | Report abuse

Anonymous-- We plan to have a gallery where readers can submit photos at some point

Posted by: Jason, Capital Weather Gang | July 26, 2008 4:06 PM | Report abuse

PM Update: 88F, 29.96, falling.

Sterling is now posting a thunderstorm threat for Tuesday PM "as the frontal boundary moves back north". [Not welcome due to the Clarendon Ballroom swing dance!]

Otherwise the tropics seem to be quieting down a bit. There's one rather robust wave approaching the Windward Islands and dissipating T.S. Genevieve in the east Pacific. This has been the most active July down there since 2005 or so it seems.

Something to watch on the maps: There seems to be a nice MCS or thunderstorm cluster on IR sat maps in AL and MS. In addition, Knoxville was reporting heavy rain. I'm not sure whether any of this gets into our neighborhood though. One interesting item on the TPC/NHC Western Hemisphere chart: a severe thunderstorm on the Colombia/Venezuela border [Could Hugo Chavez be generating a little hot air???].

Posted by: El Bombo | July 26, 2008 5:07 PM | Report abuse

Jason/Capital Weather Gang --

The NWS may be having problems transmitting warnings again.

I am seeing warning boxes on the regional radar eg.
BUT until just this very minute there were not warnings on the local office maps eg. OR on the state page eg.

NOW there are warning colors displayed on the local office pages and warnings for the appropriate counties reached from clicking on the region pages BUT there are no warnings listed via the state page.

Can you contact the weather service and let them know about this warning transmission problem? This is similar to the problems earlier this month/summer.

Posted by: Murre | July 26, 2008 5:18 PM | Report abuse

Also, there are no severe thunderstorm warnings displayed on or This is a reversal of the problem the last time I let you know about it.

Thanks! I'm off to a cookout, will keep an eye to the sky.

Posted by: Murre | July 26, 2008 5:21 PM | Report abuse

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