Thursday, December 22, 2016

The Cloudspotter's Guide Says Cumulus Radiatus [UPDATED]

Text is coming, but we're headed to the La Brea Tar Pits with our granddaughter, so first you get the pictures, then I'll add more later.  Let's just say, it was a beautiful day, and then the clouds came and it started raining yesterday afternoon and it's still raining today.

This is the updated part Dec. 22, 2016 9:30 pm (Pacific Time):

My son gave me a copy of The Cloudspotter's Guide by Gavin Pretor-Pinney for my birthday earlier this year and I took it on this trip thinking we might see some clouds.

As I started reading, I realized this is NOT your typical dry, scientific expert guidebook.
"If a glorious sunset of Altocumulus clouds were to spread across the heavens only once in a generation, it would surely be amongst the principal legends of our time.  Yet most people barely seem to notice the clouds, or see them simply as impediments to the 'perfect' summer's day, an excuse to feel 'under the weather'.  Nothing could be more depressing, it seems, than to have 'a cloud on the horizon'."

It turns out Wednesday this week in LA was an exceptional day and luckily we were able to spend the afternoon at the beach with our granddaughter, making sand castles, and playing tag with the surf as it went out.  It was warm and delightful.  The picture below is of Santa Monica Bay from Venice Beach.

And having read the introduction of the book, I was more interested than worried as clouds formed on the south western horizon and seemed headed our way.

I had read most of the chapter on cumulus clouds too.  These are low clouds.  According to the visual table of contents, which shows different clouds at different altitudes along with the Chapter name and number, cumulus clouds stay under 10,000 feet.  They also are the most commonly rendered clouds in art work from children's books to classical painting.  And they tend not to mean rain.

The author tells us that clouds are classified by genus and species and varieties, which made me feel pretty ignorant since I didn't know that. Animals and plants, yes, but clouds?  That was new to me.  Four species of cumulus cloud are listed:  humilis, mediocris, congestus. and fractus.  And one variety is listed for mediocris - radiatus.
It says about radiatus:
"When cumulus have formed into rows, or 'cloud streets', which are roughly parallel to the wind direction."

Now, the title of this post is a bit misleading.  The Cloudspotter's Guide didn't say that the clouds I saw were radiatus.  I read the book and looked at these clouds and thought - this must be what the book was talking about:  radiatus.

By that Thursday morning there were a lot more clouds and by evening it was raining.  But The Cloudspotter's Guide does say:
"Although Cumulus is generally associated with fine weather, any cloud can under certain conditions develop into a rain-bearing formation, and Cumulus is no exception.  The innocuous Cumulus humulis and mediocris  can on occasions grow into the angry, towering Cumulus congests, which it must be said is anything but a fair-weather cloud."

It was still raining when we left this morning, but cleared up in the afternoon.  Spent the day in the Pleistocene era -with giant sloths, mastodons, and other late ice age creatures.  More on that in another post.

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