The next time I find myself tutoring a math student who needs a reminder of what a tangent line is, or a physics student who is learning about angles of reflection, I really must tell them about noctilucent clouds. I suspect that most people who live in the mid-to-high latitudes have seen them but few have given them much thought.
Click on the above image. That will take you to the web site for NASA’s AIM mission. Scroll down just a wee bit to where it says Noctilucent Clouds in Motion. Then click on the image just below that title and watch a short but amazing time-lapse video to see something you have probably never imagined. Unfortunately, I could not find a way to embed a link to the video in this page and I don’t believe I have the right to redistribute a copy of it. I will try to keep checking the AIM site to see if they move the video to an archive page. If I see that they have done that I will update this post with the new location.
The site includes many more images of these stunning atmospheric physics phenomena but I particularly recommend this page for a brief history of NLCs and a simple diagram explaining how we are able to see them.
Clear summer evenings, after the sun has set and the sky has darkened significantly, are the perfect time to look for noctilucent clouds. Binoculars are not required but, if you have them available, use them to take a closer look at the structure of any NLCs that you see.