Earth Matters

Mammatus Clouds over Oklahoma

May 24th, 2013 by Adam Voiland


Earth Observatory reader Warren Bonesteel sent us this shot of mammatus clouds over Duncan, Oklahoma, on May 20, 2013.  They were taken at about 7:00 p.m. CST, a few minutes after a large supercell storm passed. The same storm system spawned a violent tornado that devastated the nearby city of Moore. While most clouds form in rising air and have flat bottoms, mammatus clouds have pouch-like protrusions caused by sinking air that hang on their undersides.

Mammatus clouds can only form if the sinking air is cooler than the air around it. The sinking air must also have high water or ice content.  Though they are often associated with thunderstorms, the clouds are harmless and usually form in pockets of turbulent air after the worst of a storm has passed. They are not an indicator that a tornado is about to hit. You can learn more about mammatus clouds from  Astronomy Picture of the Day, Earth Science Picture of the Day, AccuWeather, CBC News, EarthSky, and UCAR.

Did you have other dramatic shots of this storm system that you would like to share? Please send them to I’ll add the best of what we receive to this post.



The photo below was taken on Sunday May 19, 2013, by Darren Purcell.  It was taken in advance of the storm that hit Norman, Oklahoma.


8 Responses to “Mammatus Clouds over Oklahoma”

  1. Ed McCarvill says:

    Your descriptions of clouds are most interesting, especially the sag bottom dimples of colder and thus heavier moisture. Pardon my hobby protruding here like the sag-bottoms in which electricity could form between the warmer and colder portions of each mammatus cell.
    Is it possible to discover if there is an interior rotation around each stretched out sag’s central vertical axis? If found as so, that discovery would announce that a possible collimated stream’s properties are in place in each separate mammatus cell. By understanding electron properties it is simple to understand the oft found jetting collimated streams found at opposed polar sites of proto-stars and galaxies black holes.
    I hope this gives you pause in thoughts.
    Unfortunately, I am unfamiliar with computer and Internet terminology, so RSS 2.0 means nothing to me, which means an email reply would be noted by me, not the other thing.

  2. Paul Laplante says:

    You can pretty much find out anything about clouds at the Cloud Appreciation Society. Along with many interesting photographs submitted by society members. Enjoy

  3. thedametruth says:

    awesome shot! I never saw a cloud bank like this!

  4. Aaron says:

    Fascinating photo. I had never in my 82 years seen anything like it. Thanks for sharing.

  5. Karla Matthews says:

    The reason people haven’t seen these are because they are new, not rare NEW. This is the aftermath of an area being HAARP’d with high frequency waves that produce severe weather patters. Keep an eye on Florida, it’s been HAARP’d for the last four days with low to high frequency waves. Mad scientists playing God. These evil people need to be stopped.These are not the clouds of our childhood.

  6. Cassandra Morrison says:

    Karla, have you thought about getting professional help? Mammatus clouds were around when I was a child and I was born in 1950. In my youth people thought they meant a tornado was coming. They don’t. But they can be the result OF a tornado in the area.

  7. George Orwell says:

    Cassandra, the great dissuader of critical thinking. Have you ever thought about becoming interested in current invents instead of brow bashing society from way back in the 50’s? Mummatus clouds are a rather new classification of cloud. There are many proposed ideas on how they are formed, of the most popular hypothesis being they are man made by means of cloud seeing with metallic paper or oxides. Another popular theory is that they are a consequence of HAARP activity, as per wiki.

  8. matt says:

    Yet another hardcore believer of sc-fi. They may have been recently named and studied, but as you have just been told, they have been and will be around for ever. Maybe not your ” run of the mill ” cloud, but still, a cloud. And as for using”wiki” for hard evidence, well that’s laughable. It’s not like wiki has got it wrong before now is it. Any and every fruit cake out there can and does contribute towards a wiki explanation for anything you can think of. Hardly satisfiable evidence in my honest opinion.