Eyeing Noctilucent Clouds

Folks lucky enough to be outside the past night or two in parts of North America and Europe have been treated to fine displays of noctilucent clouds.  These are ghostly looking clouds that seem to glow in the sky long after the Sun has gone down. People in northerly latitudes see them quite often, but it has been rare to see them as far south as France, for example, and certainly very rarely over southern Nevada and other mid-latitude locales.

Noctilucent means “night-shining” and nobody’s quite sure exactly what causes these glowing apparitions. They first appeared about the time of the eruption of Krakatoa in the 1885, and they are likely related to the distribution of fine dust in the upper atmosphere. But, where that dust comes from (it’s tough to waft dust from volcanoes UP to where these clouds form) is still a topic of great discussion among atmospheric scientists. It’s possible that dust from space is involved in some way.  The clouds themselves are made of water ice crystals that have formed around tiny particles of dust. They seem to be occurring more frequently now, over wider ranges of latitude. It’s very possible that their spread is related to global warming — also a topic under a lot of discussion these days.

Want to know more about these clouds?  Go here and here to read about what some atmospheric scientists have to say about noctilucent clouds. And, by all means, go outside tonight (and maybe the next few nights) and keep an eye out for glowing, wispy clouds like the ones in the picture above.

***

Thanks to everyone who has written to wish us well during our recent move back to Colorado.  We’ve made it in fine shape and are settling in nicely.  It’s good to be back online and sharing science with y’all!