Lenticular clouds over the Boulder foothills

By Phil Plait | October 21, 2009 4:00 pm

One thing I love about Colorado is that things I used to think were rare are actually rather common here. For example, lenticular clouds are lens-shaped (hence the name) clouds that sometimes form when air flows over the mountains in a certain way. Where I grew up on the east coast they were non-existent, but here, a few miles downwind of the Rocky Mountains, I see them pretty often.

While I was at the gym the other day I saw a nice one, and posted a pic using my phone, but the cloud is a bit small and hard to see. After my workout, I got home, climbed onto my roof and, using a better camera, got this shot:

Sadly, by the time I got home the formation started to falter, but you can still see the elongated, oddly-sculpted shape. The knobby formation on the ridge line is called The Devil’s Thumb, and is located south of Boulder on the foothills.

I took a second picture at a faster exposure time so that details weren’t washed out, and that one is on the right (you can click both to embiggen).

I remember seeing lenticular clouds practically every day last fall, so I’m looking forward to seeing better ones here soon. They’re very cool, and another in a long list of things you might miss if you don’t simply look up every once in a while.

CATEGORIZED UNDER: Cool stuff, Pretty pictures

Comments (25)

  1. Sarah

    Someday I hope to get a close-up look at one of those. Glider pilots come from all over the world to enjoy the Sierra wave ( see awesome movies here about wave near Tahoe: http://hdsoaring.blogspot.com/2008/05/sierra-wave-and-return-large-650mb.html )

    Looks like the Denver area was working pretty well too that day!

  2. Those are no clouds my friend… it’s a fleet of BalloonBoys!

  3. Jason Patterson

    I was under the impression that lenticular, just like lens, comes from the word lentil, which preceded both. Lenses and lenticular clouds are lentil-shaped. :-)

  4. This is totally unrelated to your post about clouds, but here’s a nice article on vaccines. It was written by a pediatrician in New York city.

  5. dragonet2

    I’ve seen those up in the Rockie Mountains. I want to one day personally witness those roller clouds in Australia.

    Then again, I always know what the sky looks like, and don’t understand those who refuse to look up.

  6. Spectroscope

    Well worth looking up for. Usually (esp. at night) clouds are something I’m happy to do without. But these ones do seem pretty good. :-)

    Do they give you rain or hail? Or just float on by?

    Do they have a technical name lenticular cumulus or strato-cumulus or something?

  7. tim

    I sure do miss the Flatirons over Boulder. And they make for some nifty clouds!

    We get lenticulars coming off of Mt. Rainier that are pretty spectacular. I think they’re mostly in late summer.

  8. gypkap

    I see lenticular clouds over the Sandia Mountains east of Albuquerque now and then.
    Completely off topic: the Sandias got snow today at higher altitudes, and Albuquerque got much needed rain.

  9. Kevin

    @ Spectroscope – the official designation is altocumulus standing lenticularis

    I actually saw lenticular clouds in Michigan a couple of summers ago. Freaked me out. :)

  10. idahogie

    Saw my first (and only) anti crepuscular rays right near you (Louisville) back in 1996. Those were amazing. I pulled over at a friend’s house and dragged him out to show him – I had no idea what they were.

  11. dragonet2

    The most exciting thing I’ve seen in Kansas City is mammatas clouds. Can’t find the photo I took of them. though.

  12. Give it a shot with a polarizing filter, and with an IR filter (set the camera in B&W mode). Both of these make for dramatic cloud shots.

  13. Ausduck

    Cool clouds, thx 4 the pics!
    Darn it, BA , it looks like you have an awesome view from y0ur house without the clouds! :)

  14. Rob

    MichaelL may jest about the actual objects represented here, but my local cult (Ramtha in Yelm, WA) actually believe these are spaceships that aliens are flying into the mountains (to the middle of the hollow earth). You see, they just look like clouds to us because our brains aren’t prepared to see what they really are. The cult has died down a little lately but was rather large at one point, famous members include Salma Hayek and Linda Evans.

  15. Spectroscope

    @ 9. Kevin Says:

    @ Spectroscope – the official designation is altocumulus standing lenticularis

    Thanks! :-)

    Anyone here seen noctilucent clouds – high altitude night-time glowing clouds?

  16. Just me

    I need to look through my photo archives, because I know I saw and photographed a beautiful bank of lenticular clouds when I was driving across country once.

    @14. Rob
    Really? Salma Hayek is part of the Ramtha cult? I had such high thoughts of her until now. Sigh.

    I think the freakiest clouds I’ve seen were these green inverted cotton balls across the sky like an upside down mattress. I believe those are precursors to tornadoes. Is that true? It was very windy that day, but I never saw a tornado.

  17. Ugh, i hate lenticular clouds… Mountain wave turbulence.

    But yes, I will agree, they are cool to look at. Just in the aviation world, you want to avoid them. That and virga too. Unless you like replacing your fillings!

  18. CJSF

    One thing that surprised me after moving to Florida was that there are lenticular-like clouds here quite often. They form over the top of towering cumulonimbus clouds, presumably in the same manner as those forming over foothills and mountains. However, they are quite small. Occasionally I’ve seen them relatively isolated in the sky, but I assume they are forming in the same manner.


  19. Stephen

    I saw a lot of those when I lived in Boulder too. Here’s a great shot of clouds rising over a mountain that I took in Estes Park.


  20. mike burkhart

    Yes these clouds are sometimes mistaken for ufos another thing mistaken for ufos I think is secret aircraft (I’ve had an intrest in aircraft in studying I came to this conclusion) in the 50s there was reserch in saucer shaped aircraft in fact the first report in 1947 that started all this may have been a flight of flying wings another type of aircraft reserched In the late 80s there were reports of triangle shaped ufos in Europe at the time the f117 at the time top secert was being deployed to nato air bases I think these people thought the f 117s flying to these airbases were ufos I konw some may disagree with me but this what I think is just one rational thing ufos could be

  21. Chris

    Every once in a while you can see some (small) lenticular clouds off Mount Greylock here in MA. It’s uncommon but not unheard of and sometimes they’ll post pictures in the Lifestyle (!) section of the local paper.

  22. stevesliva

    Climbing magazine just had some news about the Devil’s Thumb:

    Climbing that overhang you see in your photo turns out to be really difficult. Go figure!

  23. Larry

    @ Spectroscope asked –
    Do they give you rain or hail? Or just float on by?

    These clouds are formed exclusively when you have a high and reasonably laminar (smooth) wind flow over something big enough to cause a region to exist where cloud can form. The technical background involves the air speeding up and an associated pressure drop to get around the obstacle, but the key is that the temperature drops below the dew point in that reagion. The cloud appears to be stationary but is actually VERY active-forming on the leading edge and dissipating on the trailing edge of the visible cloud.

    I don’t recall EVER seeing any sort of precipitation from a lenticular cloud…I’m not sure that that is possible, given how they are formed, but I’m open to be surprised, too. :-)

  24. For a trailer on a 32 minute documentary of a soaring distance record using the lenticular clouds, go to: http://www.youtube.com/watch?v=YAKYNAi0P7Y

    FYI, if you want to buy the full 32 minute HD video, go to: http://hdsoaring.blogspot.com

    And thank you to Sarah, whomever you are , for citing my video in my blog in the first post above. I shoot HD video from the cockpit of my gliders (not hang gliders) for education and instruction on using wave clouds (lenticulars) for cross country soaring flights. In the video we discuss planning, preparation and tactics for flying 1,200 miles in one day without an engine. The world record is almost 1,900 miles in one day set in Argentina a few years ago. That’s from SF to Chicago with no engine in one day! Yet there is very little research on these, other than a few crazy glider pilots who either want to break records, or in another highly specialized project, to go to 90,000 in wave produced by the Polar Vortex: http://www.perlanproject.com/

    For me, this is the best science there is!


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