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Sunset Mammatus Clouds - Dec 1st 2006

Below is a series of images showing a spectacular Mammatus display which passed over Maghera on December 1st 2006 at 17.25 UT (second display in four days) moving from SW to NE. This display was enormous, boasting giant bags and dark complex swirling structure which covered much of the entire sky. The bags displayed a sand or golden colour due to the low elevation of the Sun. It was raining heavily at the time so my camera was covered in rain drops (you can see some of the drops on the images). I was out in a T-shirt getting a proper soaking as I had to react swiftly to catch this display so the neighbours most likely thought I was crazy.

A beautiful sunset rainbow was also present in the N-NE sky. This was an incredible display. It really did look like Armageddon. Thanks to Conor McDonald for again alerting me to this display in short notice via text message. All images taken at ISO 62, Shutter speed 600/sec at F/3.2 using a Fujifilm finepix S5600 5.1MP camera handheld. I ended up with 70 images of this short-lived display because it passed over at high speed and was soon gone. There was a convective outlook issued on this day for isolated thunderstorms due to the passage of an active cold front so this mammatus display had formed under the anvils of embedded cb cells at the back end of the front.. Here are a selection of the more interesting images.

Camera getting soaked here. The dark area to the L is falling precipitation. I'm standing in my back yard in a t-shirt which was already soaked through. Facing S towards Slieve Gallion. Clouds are moving swiftly from R to L (SW to NE). The Sun is low but bright in the SW where it was clear and producing this stunning colour on the complex mammatus structure above. To give you an idea how wide spread this display was I could see pouches to my R, behind, L, and straight ahead at the same time, including the zenith which was completely covered.

Another rain drop makes it onto the lens, although the rain was easing now. Just before this passed over it was really intense, loud enough in fact to hear from indoors with the television on. What struck me most was the extreme low height of the display, I felt like I could have thrown a stone into the clouds. Not only where the mammatus pouches hanging low and growing in number by the min, they were also swirling at the same time as if there was some kind of chaotic motion going on with the convection. Cbs which form during the Winter months tend to be of the low-topped variety which explains why the display was at such a low level. The tropopause is much lower at this time of year due to the colder temperature so the anvil hits this ceiling and appears low-level. These look very different from the Summer high level anvil tops.

Awesome structure over my neighbour's rooftop. This is looking 1/4 of the way to the zenith in the SW.

Wide angle vertical shot facing S again.

Brilliant structure here. Rain is still falling.

This is very strange looking. Lots of smaller mamma forming on the larger bags.

Turning the camera around to the NW now . That's my house rooftop to the L. Looking half way to the zenith.

Turning around to the SW, and again near the zenith. The display is over my other neighbour's roof now. Large pouches to the upper R. These are all wide angle images.

Now the NE where the front was heading. A stunning primary and secondary rainbow formed on the precip curtains which were falling with fine structure behind those rooftops. The colours of this bow were phenomenal, so intense and rich. By the way the colours have not been adjusted here, these are all straight from the camera. Alexander's Dark Band can be seen between the two arcs.

The bow 'cuts off' just as it meets the large mammatus pouches.

Now E of N.

Back to the NE as the cold front continues on it's journey. Both bows are still visible with mammatus above. The sky was extremely dark under there.

Further away and dropping lower in the sky. The mamma almost seemed to be at roof level, but of course they are much higher than this in reality.

That was the end of the display. It was swift and amazing at the same time. I'm glad I looked outside when I did and had timed it just rite to get these images for the record, if Conor's message had been delayed I would have missed it completely. It's good to have people to tip you off to any sudden events like this. Even looking back on this display now, several years later, fills me with awe. I can recall this evening vividly, I made a vow that I would capture every mammatus display in the future, which I think I have succeeded in doing. My only regret is that I didn't catch this from the country, it would have looked amazing over the green fields and trees. At least the houses in the images gave that Earth-sky-Human connection which I always like to see. Thanks for reading.

Martin McKenna

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