[pct-l] Re: katabatic, adiabatic, and other noteworthy tics

[jeffmoorehead1 at cox.net (Jeff Moorehead)]

i like how that last paragraph put the whole post 'on topic' and the last 
sentence even rhymed...
i am like you-- i can't seem to get enough of that understanding of how 
local meteorology is influenced by the ever changing global solar condition 
and those wonderful laws of thermodynamics... nerds we are


----- Original Message ----- 
From: "Brett" <blisterfree@isp01.net>
To: "Jeff Moorehead" <jeffmoorehead1@cox.net>; 
<pct-l@mailman.backcountry.net>
Sent: Monday, February 07, 2005 6:58 PM
Subject: katabatic, adiabatic, and other noteworthy tics


>>>>If you descend into the desert from the dry side (east side in CA) of
> mountains, the temperature increases at a rate faster than it was 
> decreasing
> as you climbed the west side. That's why the deserts to the east of the
> Sierra are not only dry (the rainshadow effect) but so damn hot!<<<
>
> Slightly OT, but www.weather.com now offers 30+ day forecasts. That's 
> right - a whole month's worth, for every dang place in the country. Okay, 
> so it's more like the farmer's almanac beyond the 10th day (or is that the 
> 2nd?). In fact, after day 14, all they offer are statistical averages for 
> that calendar date at that locality.
>
> This information is utterly useless for planning purposes, and is not a 
> forecast in any way. Then again, maybe they know that, since much of their 
> tv programming seems aimed at garnering the weather geek quotient from the 
> sum total viewership.
>
> But the information is very useful for understanding how weather, and in 
> particular temperature, patterns shift over the course of days, weeks, and 
> seasons. In most regions of the country, both high and low average daily 
> temperatures are now, in early February, just beginning to climb from 
> their winter minima. Like the hours of daylight as we trend toward spring, 
> this upward creep in temperature begins slowly at first, then picks up 
> steam as the sun gains greater dominance over our hemisphere. Hours of 
> daylight increase most rapidly toward the vernal equinox, and then 
> increase more slowly until the summer solstice. Temperatures follow a 
> similar pattern, but lag behind the gains in daylight, much the same way 
> the ocean's temperature lags behind that of the air.
>
> So everyone, on average, is currently gaining heat as well as light. But 
> some areas are gaining heat much more quickly than others. These tend to 
> be the regions with the greatest differential between winter average and 
> summer average temperatures, especially where the length of time between 
> these extents are the shortest.
>
> Take a gander at Tucson, Arizona for example, my old home town. Currently, 
> average daily high temps are climbing by about 1 degree per week. However, 
> in a few weeks from now, they begin to gain 1 degree every 5 days. Then a 
> week later, every 4 days. By mid April, the dry desert air, minimal ground 
> cover, and strong unfiltered sunlight allows that air to climb 1 degree 
> every 3 days. I'm not sure what happens next, as WC "calendar" doesn't 
> progress beyond this point yet. However, having lived there, I believe 
> every bit of it. Whereas the northeast, my current locale, hails March "in 
> like a lion, out like a lamb," it seems the Sonoran desert's seasonal 
> adage best applies to the month of April. "In like a lamb. Out like a 
> well-done goat."
>
> The PCT is a "mountain trail" that happens to descend into the desert at 
> various places. Springtime temperature differentials between the two 
> regions can be amazingly pronounced. A thru-hiker might prefer to hike the 
> desert when it's cool, if not for all the snow still up high. Or hike up 
> high without a trace of snow, if not for the sweltering conditions down 
> below.
>
> - blisterfree
>
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