Ticker for August 24, 2006

                
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August 24, 2006    August 24, 2006    August 24, 2006    August 24, 2006


The Tell-Tale Arc

(Hearken! And observe how healthily yesterday's anvil can tell you
the story.)

We are each a history; a vessel; a collection of memories. And when
we share, when we communicate, what we are doing, in essence, is
painting a situation with those memories. It's what people do.
Sometimes we like to call those memories "insight", "wisdom", or
"knowledge" but are these things any more than transformed memories?

And sometimes, we share our history without even trying.  We reveal
parts of our histories through scars, clothing, expressions, phrases
we picked up along the way. They all provide insight into the past
that shapes our present and our presence.

Well, nature can do the same. Take last night's thundershowers.
Here's a picture snapped southward from the back yard of a
randomly-selected climatologist:



This isn't the business end of the storm ... it's the western parts of
its "anvil", the attractive anvil-shaped cloud that extends miles away
from the updraft. And, its beauty is intrinsic, but it's also forensic!
It tells a story, a history of sorts, if you know what to look for.

Look closely at that picture. You may notice what you've seen hundreds
of times before: the big anvil shape is actually made up of a set of
nested anvil-shaped components: a well-defined shape on the interior,
and more obscure, less-well-defined shapes extending beyond that.
We've marked up three such shapes here (they showed up much better
to the naked eye, we promise):



The key here is to remember two things:

1. What makes an anvil: The anvil is the divergent top of the
storm's updraft. At this level, very stable air impedes its
upward progress and it spreads laterally.

2. Storms - even "typical summer storms" like this one - are
a pretty violent place, in general. Updrafts tend not to
survive very long before evolving, cycling, collapsing or
getting replaced by a younger brother.

Finally, we arrive at an explanation. The "outer anvils" are remnants
of past updraft regimes. They still drift outward, diluted by time and
no longer supported by the current updraft regime. After the updrafts
weakened, they either were revitalized or replaced after a pause.
The innermost anvil shape testifies to the most current updraft regime:
it is supported by a viable updraft so it is well-defined and solid.

And so there you have it. Just like people, thunderstorms have the
ability to reveal some of their history in plain sight. And this
particular storm carries with it the signs of at least three life
phases.

It is almost Poe-etic.