Every week or two, over the past several months, cloud-spotting friends have kindly sent me e-mails with attachments of some very beautiful clouds hovering over Mount Rainier. The clouds are known as altocumulus lenticularis, lens- shaped clouds also known as "lennies" or "flying saucer clouds."
Each e-mail includes the same set of photographs--taken from around Tacoma. Each e-mail, forwarded to me, has been forwarded to my friends--from a colleague, a friend, or in one recent case, a "cousin in Greece via my father in Colorado." The source of the photographs is unclear. I would love to know who initiated the e-mailing of this batch of photos. I would love to thank them for starting this wave of e-clouds, for moving these phenomenal clouds around the globe in a way the Jet Stream cannot. And I would like to thank my friends for sending them along to me.
Here is the phenomenon: These clouds form when stable, moist air moving on a moderate wind is forced to rise upward over a mountain. The air condenses as it rises up the windward flank, forms a visible cloud, and then begins to dissipate as it sinks on the leeward flank. These clouds form over mountain peaks, notably in Washington State, over Mount Rainier. If you are visiting Mount Rainier National Park on a day when these clouds are out, watch them with your binoculars; it may look like the cloud is hovering over the peak, but you can see the edges where the cloud actually forms and dissipates to create this illusion.
Speaking of illusions, in 1947, a business man named Kenneth Arnold, started the UFO craze by reporting to the Associated Press that he had seen "saucer-like" objects from his small plane as he flew over Mount Rainier. The rest is "history."
So, for your enjoyment, here are is the set of well-traveled altocumulus lenticularis. All photos are of Mount Rainier except the last one,which is a stunning Lennie over Mount St. Helens before the 1980 eruption.
NEXT BLOG: Mount St. Helens and the Cloud of 1980