December 15

Noctilucent Clouds: Season Underway

‘Tis the season to head south and play with nature’s hide-and-seek masters. I’m talking about the never-always seen, but always gorgeous noctilucent clouds. Okay… maybe that’s an unrealistic proposition. Antarctica or the Arctic Circle likely aren’t in our vacation plans anytime soon. I’ll use this blog to ‘transport’ us there. You’re welcome. Now we don’t have freeze and still see one of the most beautiful natural occurrences over our planet.

Always bundle up if you go cloud hunting on these fellas! They only occur in the coldest and highest places on (or in this case, above) Earth. That’s the mesosphere (which lies about 50 miles or ~85 km up!). There, the thermometer has plummeted below -225°F! That’s quite a limbo down the mercury.

So, what are noctilucent clouds?

Noctilucent (night shining in Latin) clouds are very picky. And by that, I mean they require A LOT out of you just to see. NLCs form when water molecules cling to fine atmospheric debris (such as dust or even remnants of disintegrating meteors) and freeze to form ice crystals. They are NORMALLY too faint to be seen many times because it’s just too bright outside. Dawn and dusk (better time) are the only 2 parts of the day to view them. That assumes you have a clear sky 50+ miles up.

Also, the closer to the poles you travel, the better the chances of seeing them will be. But even traveling north through Canada or hiking south through the Andes Mountains  will not guarantee a successful sighting. Moral of the story, don’t forget a camera if you ever go hunting for these bashful clouds. Take a photo… it’ll last longer. Take advantage of the good, cloud-viewing fortune because you never know when you may hit the window of seeing them again.

What do they look like?

How about enough of the nitty-gritty since you may be a visual learner? Let’s actually see what they look like! 1st, we can gander at what the satellite’s eyes see over Antarctica. Below is a series of images taken November 2016 from NASA’s AIM spacecraft, courtesy of Space.com.

Noctilucent clouds shining over Antarctica from Nov. 17 through Nov. 28, 2016, as imaged by NASA’s AIM spacecraft. Credit: NASA/HU/VT/CU-LASP/AIM/Joy Ng, producer

 

Here’s another satellite look of the bright clouds taken back in 2014. This time in a more localized view. Source: EarthSky.

Noctilucent clouds over Antarctica as seen in November, 2014 by NASA’s AIM spacecraft.

Noctilucent clouds over Antarctica as seen in November, 2014 by NASA’s AIM spacecraft.

AIM launched back in 2007 on a dedicated mission to study night-shining clouds and the mesosphere. Data collected from the mission has shown that the noctilucent cloud season can start anytime between Nov. 17 and Dec. 16 in the Southern Hemisphere.

Next is the actual beauty in full view of the human eye. Especially relevant is this photo taken over Kuresoo bog, near Viljandimaa, Estonia.

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It’s all about the angle

NLC’s are unique, in that they are only seen when sunlight illuminates them from BELOW THE HORIZON near the north or south pole. Fast Fact: This is the only species of cloud that is always better to see when the sun is below the horizon.

The image below shows the best way to see these clouds. Since they are so high up there, you could be looking well over 100 miles up and out toward the cloud. At this time, you (the Observer dude in the below image) will already be outside of the sunlight ‘zone’. Fancy that! If you would like to learn even more, they are part of much brighter clouds called polar mesospheric clouds.

 

Figure 3. Showing how to properly view NLC's. Image courtesy theflatearthsocity.org

Showing how to properly view noctilucent clouds. Image courtesy theflatearthsocity.org

 

– Meteorologist Joe Hansel

Stay classy, fellow weather warriors. Follow me on Facebook & Twitter.

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