Re: [PLUG] Waaaaay Off Topic: Thunderstorm Movement

[Rich Freeman <r-plug@thefreemanclan.net>]

On Mon, Jul 17, 2017 at 4:27 PM, Casey Bralla <MailList@nerdworld.org> wrote:
>
> When a thunderstorm moves across the landscape, is it like a wave moving on
> the ocean, or a inner tuber floating on a river?  In other words, is it the
> same moving air mass dumping rain as it moves, or is a storm an atmospheric
> wave phenomenon that moves into new air all the time?
>

I believe it is both.  I'm not an expert but it is an area of interest for me.

The entire air mass is certainly moving along the surface of the
earth.  Aloft winds are faster than surface winds and generally are a
few dozen miles per hour.

However, within that air mass there is also evolution, mostly in the
vertical direction.  Warm, humid air from the surface rises creating
large vertical clouds.  As the air rises it cools, but due to the high
heat capacity of water the moist air from the surface cools faster
than the air surrounding it (that is, as it is lifted due to being
hotter and less dense it stays hotter than the surrounding air which
is lower in humidity).  That keeps the rising air warmer than the
surrounding air and allows it to continue to rise until the water has
condensed out into plumes tens of thousands of feet high.

You also get interactions when large air masses collide.  That
involves both movement across the surface of the earth (bringing the
air masses together), and then evolution within the area as they
interact.

And you can also get weather that results from the interaction of air
with land it passes over, such as when an air mass is forced up over a
mountain.

And I believe that the air movements that are created within a storm
can also draw in surrounding air.

Somebody else will likely have a better explanation, and I suspect the
more dominant factors vary by type of storm/etc.

-- 
Rich
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