TalesOfSendingCards.com

Here it is, folks, the only evidence that the weather forecasters knew what they were talking about.  Our 20% chance of thunderstorms all boiled down to this one cloud yesterday.  But what a cloud it was!  My pic doesn’t begin to do it justice.

As a ‘know-nothing’, I’d call it a lenticular cloud riding a  little thunderhead, but there are many names for lens shaped clouds: Cap or pileus clouds, Lenticular, orographic and banner clouds, not to mention spaceships.  Any one of these refers to the round, stationary, atmospheric formations of condensed water vapor or ice crystals that most often hang out above or near high geographic formations such as mountains.  (My very own definition!)

Mount Shasta creates many beautiful cloud types and formations of water. Follow the link for more photos and copious cloud talk.

Back to lenticulars. For some reason, they fall into one of three categories—altocumulus, stratocumulus or cirrocumulus depending on something or other that I was too lazy to figure out.

If you’re feeling mentally spry, click to the AMS* or American Meteorological Society. For my present mental state, I found their definitions too long winded and circular.  (Get it?)  Just the statement of purpose was a bit on the dense or cumulus side: “The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications.”

When it comes to cap clouds, or lenticulars sitting atop a mountain peak, I think the Brits say it best:

Cap cloud

Cap cloud or cloud cap is a stratiform, orographic cloud that hovers above or over an isolated mountain peak, formed by the cooling and condensation of moist air forced up and over the peak and lenticularly shaped by horizontal upper level winds. The cloud appears to remain essentially stationary. The term is also occasionally used for pileus (Latin for cap) cloud. Unlike the mountain cap cloud the pileus is essentially an accessory cloud, that appears as a smooth cap, or hood above a cumulus or cumulonimbus cloud. The cap forms when a humid layer is lifted to its dew point above a rising thermal. This may later penetrate the pileus, which will eventually be absorbed into the main cloud body. Sometimes several layers of pileus form above one another.