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Atmospheric waves on camera!

| 9:28 am October 4, 2007 | Comments (20)

At UAH, I do a lot of research on atmospheric gravity waves, and how they affect tornadoes, and our weather in general. Some very interesting waves occurred yesterday near Des Moines, Iowa, captured brilliantly on Doppler radar and on 3 webcams, similar to the SkyCam network here. Daryl Herzmann, of the Iowa Environmental Mesonet, made me aware of this case yesterday.

We are familiar with waves moving along the top of a fluid, such as a river or the ocean. These waves can be caused by boats, etc. Water is heavier than air, and when it is lifted up above equilibrium, gravity brings it back. This sets up “gravity waves”. In the atmosphere, when the air is stable (resistant to vertical motion), and it gets displaced from its equilibrium, gravity waves are initiated in the air, too. They are typically hard to see, unless they help form clouds or rain, or can be detected on radar. We’ll discuss these more later.

In the Iowa case, an area of thunderstorms was approaching from the west, but the air in east Iowa was very cold and stable near the surface (see model sounding below). When the storms disturbed this air, a special type of train of gravty waves called an undular bore was initiated. The dense, cold air near the ground acted almost like a shallow pond, and the storms disturbed it, like a person throwing a rock in a pond.

dsm-sounding.PNG

A train of 4 waves was set up. In waves, you may have noticed that the motion is back and forth as well as up and down. Radar picture from Des Moines, Iowa NEXRAD shows this…with green showing winds towards the radar, and red showing winds away from the radar, one can see the wave features moving SE, and the alternating winds from SE to NW!

dmx-1458-v.PNG

Using software we often use in analyzing weather systems at UAH, we show a vertical cross section through the waves (looking at them from the side), where they also show up nicely. In the areas to the left of green, inbound velocities and to the right of red, outbound velocities, convergence and upward motion produces clouds.

radar-cross-section-130.gif

If you watch the videos below (from Iowa Mesonet), you can see 3 or 4 dark cloud bands (due to the convergence and upward motion caused by the waves), with clearer areas between them, caused by downward motion due to the waves! Wow!

iowa-movie-1.PNG

{vidavee id=”2687″ w=”320″ } Click here for movie.

You can also see the pressure (left) and the wind direction (right) oscillating back and forth very quickly at Des Moines, with high-resolution surface data below.

des-moines-bore-3.PNG

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  1. Zachary in Blackwater Macedonia says:

    Very awesome… thanks for these informative posts!

  2. Thanks for the info. Can a radar show wind velocities without rain or was it raining?

  3. mark says:

    Any correlation between these waves and making an actual identification of whether a tornado is about to touch down as opposed to a storm in rotation likely to produce a tornado?

  4. david harris says:

    Looks interesting but really have no idea what the waves mean.

  5. Beth says:

    Awesome, thanks so much! I felt this phenom once in Indiana in the flat open area in the middle; at least the people with me said that is what it was. The wind was forth and back and very fierce. It was raining and I wonder does it always rain during this action.I actually got this link from the NASA newsletter.

  6. betty says:

    Wild!!Awesome! I am wondering if some of the turbulent weather on the Rocky Mountain Front is subject to this phenonmena? The cloud formation appear simliar.

  7. Ted Edwards says:

    Very impressive. I couldn’t watch the movies because I don’t use Windoze. It would e much appreciated if in future you would simply attach *.mpg (MPEGs). AFAIK, there is no operating system that can’t cope with those.

    Ted

  8. Debby Reisman says:

    How does this type of cloud relate to the “morning glory cloud?”

  9. #8; My thoughts exactly! Some years ago I saw a documentary about the awesome Australian “morning glories”, where a bunch of micro-lights and gliders were riding them. See here……..

    #7; The movies work just fine on my Tiger PB. Latest QT, flash player and Perian installed.

  10. Matt Michael says:

    I live about 30 miles north of Des Moines and as an avid soaring pilot observed this with interest. I immediately sent out an email to another pilot who lives 100 miles east of me in case it held together long enough for him to see it too.

    “Tony,
    A couple of morning glory type roll clouds just swept past our place heading east. They are outflow from the storms just west of us. My camera was dead unfortunately. You could clearly see the inflow lift on the leading edge. I could see at least 20 miles north and south along the clouds so they were at least that long. If you go to DSM NWS radar base loop you can see it pretty clearly http://radar.weather.gov/radar.php?rid=DMX&product=N0R&overlay=11101111&loop=yes

    Quite soarable in my estimation”

    After observing the radar loop for some time I added this note:

    “Based on the radar signature it’s moving about 40 mph to the southeast and currently extends from about Rhodes to New Virginia or about 60 miles in length. Could easily be longer just not showing up on the scan. There are both a primary and secondary visible on the radar and I saw 2 from here roughly 3 miles apart.”

    I’d roughly estimate that the cloud base was 1500 to 3000 feet AGL and the top of the primary was 3 to 5k AGL. I think that soaring it would have been quite straightforward, a combination of wave and ridge technique with emphasis on staying in the clear ahead of the wave. Tony replied with concern about having to land in high winds and/or thunderstorms to which I replied…

    “Actually, in many cases, including this one, the outflow boundary out-races the storms by a considerable margin. The last radar scan that still shows the boundary paints it from near Grinnel to Osceola and apparently slowing down. It’s about 20 miles ahead of the precip echos which by the way are pretty darn tame anyway. The highest winds in the whole thing occured around the wave itself and they were only in the low 20kts at best judging by conditions at passage here.”

    It might have been a trick to convince a tow pilot to launch with T’storms lurking a few miles west and the timing would have to be precise. Based on the inflow condensation I bet the lift was fantastic on the leading edge. The nice thing is that unlike the AU Morning Glory you can land almost anywhere around here for hundreds of miles. However, these are not as predictable though I believe as common as the meteorologist says in the link commentary. I’ve seen this many times over the years, sometimes way too close to storms but other times plenty far away. Sometimes the waves continue for hours after the storms completely dissapate. In this case a couple of small precip echos appeared to be generated by the waves passage. They were not too huge or persistant and I believe could have been navigated/avoided by a watchful prudent glider pilot. Sometimes these grow into monster tornadic thunderstorms which you would not want to be anywhere near in a sailplane. Determining when to latch on to one of these waves could be a tricky judgement call.

    Matt Michael
    Ames Iowa

  11. Debby says:

    a question on a different topic for this group: I’m considering going on a stormchaser tour next spring- any suggestions as to which tour group to use and the likely best time to go – I’m actually less interested in seeing tornadoes than in seeing great storm cells – love those anvil clouds and weird light.

  12. Sissy Willis says:

    What is the body of water in question? Lake Gray? The Des Moines River?

  13. dilip joshi says:

    sir
    i m working with vlf receiver here in india gujarat bhuj kutch a heavy seismic zone data is available recorded but i want to know about the high energy particle activity which is related to seismic termmer & any other solar or cosmic activity i m working as lectuerer in physics kindly sugest the books & any online matetrial concern to this U CAN HELP ME URS
    D D JOSHI

  14. Hmm! Anybody heard of the TSPS (Thunderstorm Solar Powered Satellite), patent-crafted by Bernard Eastlund (eastlundscience.com) and enacted by the United States DOE? Interestingly enough, this satellite can (and is intended to, along with various other weather modification particulars) alter storm systems with microwave frequencies capable of either agglomerating or dispersing water molecules and ionospheric plasma buildup!! Reminds me of AWIPS (owned and operated by Raytheon), which used to be legitimately natural research and reporting; now that very NOAA national weather service (weather radio, etc) is controlled and “forecast” by “weather modification” UAVs (unmanned autonomous vehicles) hooked up to radio transceiver stations all over the place. Holy moly.

    Peace.

  15. Jim says:

    I was out looking at a customer’s soybean field just before this storm came in. The cloud formations were so striking to me I snapped a couple of photos. Now I find out I observed Interesting Weather Phenomenon! Cool!

    http://www.flickr.com/photos/zeamays/1486913428/

    and

    http://www.flickr.com/photos/zeamays/1486915104/

    Toting around a digital camera with me at work has now been justified!

  16. Lewis says:

    Looks like solar cycle 24 is showing promise. Bet the sociopaths will blame it on the man made global warming LIE.

  17. [...] to really like watching Sean McLaughlin when he worked for channel 12 in Phoenix. After reading this post by Tim Coleman in Alabama, I think I’ve found another weather geek to follow. Tim explains [...]

  18. [...] and Doppler radar image of an undular bore in Iowa we posted on this blog back in October. If not, click here. These are relatively rare meteorological events. They are a form of gravity wave train which [...]

  19. Amy Trent says:

    Hi, neat web site, just curious what antispam system you use for comments since I have been hit by so many spammers on my web site.

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