Newsgroup sci.geo.meteorology 29734

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On Tue, 21 Jan 1997 02:51:05 -0600, klaas@nl.compuware.com wrote:
>In December 1997 a traveler (I forgot his name) will 
>circumnavigate the world with a large balloon of 150 meters 
>high at an altitude of 35 km.
>
>What I wonder is that he can see stars in the daylight at 
>that altidude ? Simply taken, one can calculate the 
>limiting magnitude for a given pressure as the scattering 
>(and the brightness of the sky background) is equal to the 
>number of air molecules per volume and thus the pressure. 
>Not completely, as due to the Rayleigh scattering at lower 
>pressures only shorter (and less visible) wavelengths will 
>be scattered, so this is even more favorable for the 
>extinction of stars due to less brightness in visible 
>wavelengths. But for simplicity, ignore this.
>
>At 35 km the air pressure is .0125 bar. That means that an 
>observer can detect stars which are .0125 as bright than at 
>sea level pressure. That means in stellar magnitudes 2.5 * 
>log10(.0125) = 4.8 magnitudes gain. That means that a star 
>of magnitude 0 (e.g. Vega) is as easily to detect as Venus 
>in the daytime at sea level (or easier because most stars 
>are farther from the Sun which makes another gain up to 1 
>magnitude).
>
>At the cruise altitude of an airliner (10 km) the gain is 
>about 1.5 magnitudes. This can make Jupiter (or even 
>Sirius) when placed favorably easy to detect. But stars are 
>still no option. I tried once Capella during a flight but 
>without success.
>
>Any ideas on this ?
>
>Klaas
>-------------------==== Posted via Deja News ====-----------------------
>      http://www.dejanews.com/     Search, Read, Post to Usenet
Klass,
   The Lockheed SR-71(high altitude/high speed recon aircraft) has a
Star Tracking Navigation System onboard and can track stars day &
night, on the ground or in flight.  As long as there are no clouds,
the crew has to make sure it is tracking stars before takeoff.  How it
does this, I have no idea.
Jeff Krob
jkrob@shore.intercom.net

Twisted STISter wrote:
> 
> If you have a window seat on the side opposite the Sun,
> you might be able to > see the shadow of the plane on
> the clouds below. Sometimes, surrounding the shadow,
> is a rainbow/halo called a 'glory'...
This and other phenomena are discussed in a delightful little
paperback I bought years ago - Science From Your Airplane Window
by Elizabeth A. Wood.
Ken

Richard Townsend (rhdt@star.ucl.ac.uk) wrote:
: On Wed, 22 Jan 1997, Daniel Kaplan wrote:
: > Jay Reynolds Freeman wrote:
: > > 
: > >     One can do interesting astronomy, or at least astronomy-related
: > > work, from a window seat of a jetliner.  There are several ways to
: > > detect the curvature of the Earth.  The easiest is to use liquid in
: > > one of those thin-walled clear cups as a level, and sight across it.
: > 
: I assume you've heard of the Kuiper Airborne Observatory, an infra-red 
: telescope looking out of a hole in the side of a 747?
I thought it was a somewhat smaller plane; IIRC, it was recently retired,
and the 747 to be used for its successor has been procured. I think the KAO
was a 36" infra-red scope, and that the successor will be a 100" device.
That ought to produce some quite impressive pictures; even if it can't
do science in the same wavebands as ISO, it's big enough that we can
start seeing faint things.
--
Tom
The Eternal Union of Soviet Republics lasted seven times longer than
the Thousand Year Reich

Mik Clarke  wrote in article
<5c2eaq$kve@ausnews.austin.ibm.com>...
> In <853677281snz@daflight.demon.co.uk>, Hugh Easton
 writes:
> >In the early 1980's, a multinational project was set up to collect and 
> >analyse samples of ice which originally fell as snow up to 160,000 years
> >ago in Antarctica. The objective was to obtain information on past
climate 
> >and on how trace gases, notably carbon dioxide (CO2), might affect
climate. 
> >
Does anybody know how the ice samples were dated?

In article <5c3akp$n2u@ursa.smsu.edu>,
Redd Emmett R  wrote:
>In article <19970119180500.NAA05621@ladder01.news.aol.com> 
> eburger@aol.com (EBurger) wrote:
>: Rodney Small wrote (in response to Bill Oertell's response to vicserv's
>: 'why is the sky blue' question:
>
>An empirical answer is:  Because molecular Oxygen is blue.  (This answer 
>doesn't discount the scattering explanations.)
It also isn't consistent with the fact that the setting sun is red,
not blue.
As far as I can tell from squinting at graphs in books on atmospheric
radiation, gaseous oxygen is essentially transparent and colorless in
the visible spectrum, except for a couple of very weak absorption
bands in the far red and near infrared end of the spectrum.
-- 
Grant W. Petty                        |Assoc. Prof.,  Atmospheric Science
Dept. of Earth & Atmospheric Sciences |Voice:  (317)-494-2544
Purdue University                     |Fax:    (317)-496-1210
West Lafayette, IN 47907-1397, USA    |Email: gpetty@rain.atms.purdue.edu

Hi again,
As Hurricane GRETELLE comes close to the south-east of Madagascar,
a new hurricane is in formation a few hundreds of km north-east
from Reunion Island. Its name will be probably ILETTA, as HELINDA
is already the new name of Hurricane PANCHO which came from the
Australian area.
The last images show that GRETELLE is now very powerful and aims
directly at the coast between Mananjary and Tolagnaro.
I recall that the images are on the following anonymous FTP site:
 hostname : melusine.mpl.orstom.fr
 username : anonymous
 password : your e-mail address
directory : pub/incoming/gretelle
-rw-rw-r--   1 ftp      62         59891 Jan 23 19:09 P97012310.jpg
-rw-rw-r--   1 ftp      62         54209 Jan 23 19:10 P97012314.jpg
P97012310.jpg : Color, Thursday afternoon, NOAA-14 ascending
The eye position is:
lat = 51.4 E
lon = 20.6 S
P97012314.jpg : B & W, Thursday evening, NOAA-12 ascending
The eye position is:
lat = 50.7 E
lon = 21.4 S
You can notice the perhaps-future Hurricane ILETTA in the N-E.
Bye
Mamy RAKOTO
ORSTOM/SEAS HRPT Station
Reunion Island

> > Jay Reynolds Freeman wrote:
> > > 
> > >     One can do interesting astronomy, or at least astronomy-related
> > > work, from a window seat of a jetliner.
>
> I assume you've heard of the Kuiper Airborne Observatory, an infra-red 
> telescope looking out of a hole in the side of a 747?
  Yes, but regrettably, that seat never seems to be available when I do
business travel.
-- 
   Jay Reynolds Freeman -- freeman@netcom.com -- I speak only for myself.

I am seeking a source of daily average relative humidity data points for
selected sites in Souther New Jersey.  Is there any available data
on the Internet?
Thank you for any response!
Paul E. Schwartz
GPU Nuclear Corporation
PSchwartz@GPU.COM or
PSSHARKS@CYBERCOMM.NET

Roy McCandless wrote:
> In the 1950s, we sailed on Queen Elizabeth.  My mom said she took a tour
> that included entry into base of smokestack (?).  She says that she
> could see stars from inside.
> 
> Roy
I hate to impinge on the veracity of anyone's mother but that could only
be true if it was at night.  Also the stars are surprisingly far from
each other in the night sky.  Looking up a long smokestack at night,
unless your eyes are fully dark adapted and you are very lucky, you
won't even see one.  You'll be looking at too small a portion of the
sky.  If you do, run to the lottery tables as your lucky night as
arrived.
The sky is bright because of Rayleigh scattering.  Lord Rayleigh
discovered that when light hits anything less than 1/10 of a wavelength
in size the light is scattered.  The amount of scattering is dependent
on the 4th power of the wavelength.  Taking blue light as 4100 angstroms
and red as 6400 we find a difference of 1.56.  Raising this to the 4th
power we get about 6.  Thus, there is 6 times as much blue light in the
sky than red and we see a bright blue sky.  All this is happening far
above our heads.  There is little we can do about it.  Certainly looking
thru a long tube of any sort isn't going to change what the air did far
above our heads.  Now if the tube contained a vacuum and extended above
the atmosphere...
Actually there are a few ways of cutting thru Rayleigh scattering.  We
can use a red filter so we get only 1/6th as much light and increase the
contrast by a factor of 6.  I've used this to help find Venus and
Jupiter in the daytime.  Still a difficult task but some easier than
without the filter.
Rayleigh's equations also show the scattered light will be polarized. 
Argon molecules do the best job of this I believe.  But since the light
is scattered many times, not just once, this effect isn't that great and
depends how far from the sun you are looking.  Take a pair of polarizied
sun glasses and hold them out if front of you while you rotate them. 
You'll see the difference in different parts of the sky.
Yet another way is to enlarge the image of the sky.  When you do, you
spread the light out over a much larger area but the stars, being near
points, aren't enlarged, until we go to magnifications high enough to
see the airy disk clearly.  By using 200 power instead of 10 we cut the
brightness of the sky by the square of 200/10 or 400 times.  Much better
than the red filter or polarizing filter.  But now you must know where
to point the scope.  This trick makes seeing the brighter planets
possible during the day in a telescope though at far reduced contrast
compared to the night sky.
But going down into a well, smokestack or cave does nothing but restrict
your view of the sky.  The brightness per square second of arc isn't
changed one iota.  Nor are the stars any easier to see.
Sorry mom.
At Hyde I have heard the story like hers before.  But on closer
questioning I got at least one to admit that that is what their guide
told them would happen if they did look up the smokestack.  But since
the stack is part of the propulsion system of the ship, and a very dirty
part, I doubt if there is any ready access to them by the public, though
my knowledge of ships is near zero.  My wife was on an eclipse cruise in
the early 70's but they weren't offered a tour of the engine room or
smokestack.
At Hyde it isn't at all uncommon for a befuddled patron to be looking at
the moon and descibe it in detail while I am seeing a perfect image of
the moon on their forehead!  It is enough to make you believe in the
'third eye proponents' ;-)  They know that is what they are supposed to
see so they see it.  Never ceases to amaze me.
Rick

Glitter910 wrote:
> 
> what tim e did the sun set last night?
Where?

In article <32e79695.2885234@news.intercom.net> 
jkrob@shore.intercom.net (Jeff Krob) writes:
[snip]
>
>   The Lockheed SR-71(high altitude/high speed recon aircraft) has a
>Star Tracking Navigation System onboard and can track stars day &
>night, on the ground or in flight.  As long as there are no clouds,
>the crew has to make sure it is tracking stars before takeoff.  How it
>does this, I have no idea.
>
>Jeff Krob
It must be using infrared cameras.  The sky is just as bright in the day
as in the night at wavelengths of a few microns (micrometres).  Not just
as dark; just as bright with thermal emission.  It probably looks for 
bright planets and bright reddish stars like Betelgeuse and Arcturus, as 
well as strong IR sources which are not very conspicuous optically.
-- 
Mike Dworetsky, Department of Physics  | Bismarck's law: The less people
& Astronomy, University College London | know about how sausages and laws
Gower Street, London WC1E 6BT  UK      | are made, the better they'll
   email: mmd@star.ucl.ac.uk           | sleep at night.

Dan Evens (dan.evens@hydro.on.ca) wrote:
: Hugh Easton wrote:
: > One of the possible effects - not necessarily the worst - of a large
: > increase in global temperatures is the breakup of the Antarctic ice cap.
: What global temperature increase would be required for this?
Obviously, no *global* change in particular is necessary. How much
temperature increase would be required at the fringe of Antarctica is
another matter. Even how much temperature change locally is still the
wrong question - the right question is how much temperature change
for how long. It isn't entirely clear that the West Antarctic glacier
isn't unstable *already*, but the time scale of the natural background cooling
might have sufficed to keep it intact. Since we are now almost certainly
(despite various specious arguments) overriding this cooling, the loss of
a large chunk of Antarctic ice is entirely plausible. 
On the other hand, it appears to be implausible on the time scales
of interest to political types - if this happens it's likely to take
a few centuries. In the next century, there will likely be some serious coastal
flooding from thermal expansion, and some possible additional term, probably
but not certainly exacerbating, from glacial melt, but the glaciologists are
now fairly confident that the collapse of the ice sheet is not imminent.
Is the fact that the plausible consequence is centuries in the future make
that consequence irrelevant to the policy question? Personally, I think not.
I find it striking that as human capacity increases exponentially, the
time frame which is regarded as consequential seems to be shrinking
rather than growing.
Regarding the correlation between CO2 and temperature over the glacial
cycle, it's not news. It's well established, in fact, and is illustrated
in an alarming (but in my opinion appropriate) way in VP Gore's book
"Earth in the Balance". 
There are caveats, though. 
We know with virtual certainty that the glacial cycle is synchronized 
to long-period variations in the earth's orbit. Accordingly, the increase in
CO2 must have been triggerred in some way by those variations, almost certainly
through a mechanism involving temperature increases. Furthermore, there are
indications in the record that some periods of temperature increase preceded
the comparable CO2 rise slightly. (More precisely, had a slight phase lead -
the periods of increase do overlap.) 
From this, we may conclude that Mr. Easton's claims of *imminent* large
temperature rise are overdrawn. However, it is a serious mistake to conclude
that the paleoclimate evidence weighs in on the side of very small greenhouse
gas sensitivity.
The main reason for this is that the solar forcing alone is unable to account 
for the temperature variation of the glacial cycle absent a greenhouse effect forcing.
(Similar comments may be made for the still warmer epochs of the more distant past,
which correlate with high CO2 periods). This is true both for simple back-of-envelope
type calculations as well as for full GCM calculations.
The obvious conclusion is that some sort of temperature-mediated biogeochemical
feedback exacerbates the orbitally forced glacial cycle. Until we identify this
mechanism, it isn't clear whether it will operate if the warming is trigerred
by greenhouse forcing without the astronomical component. Perhaps the higher
concentrations of CO2 will shift the equilibrium such that this feedback mechanism
is slowed or even reversed, but perhaps not. If the feedback remains operational,
our long range predictions of the CO2 trajectory may be serious underestimates,
and matters may be worse than anticipated.
In a similar vein, the rather robust recent conclusion that expected greenhouse
warming has been masked by anthropogenic aerosol cooling is taken as reassuring,
but should not be. Since the lifetime of aerosol is so much shorter than that
of CO2, this is warming deferred, not warming avoided. It is true that the
global temperature trajectory anticipated in the next century is less steep
than that predicted a few years back. It is important to emphasize that this
is NOT because of serious miscalculation of greenhouse gas sensitivity but
rather because of neglect of aerosol sensitivity. This in turn indicates
that the change in climate patterns (aerosol forcing being local) may be more
rapid than the shallower temperature trajectory would indicate.
More important, I think, and more interesting as a moral and intellectual
question, is the fact that all these streams of evidence are pointing to
a certain sluggishness of the system in responding to human input rather than
a lower sensitivity. That is, the imminence of severe problems is rather
less than we may have thought, but the long term severity is, if anything, 
looking worse than ever. 
The first published 400 year prediction, based on a coupled model with, to
be sure, serious flaws (specifically ocean surface flux "corrections" which
really give too many degrees of freedom to tune the model) nevertheless 
is worthy of some consideration. (Manabe & Stouffer, 1993. See references below.)
The solution to the flux correction problem is mostly in getting computational
resources commensurate with the magnitude of the issue - coupled models simply
take vastly longer to equilibrate than uncoupled ones, and none has been run
long enough to do this. It seems likely that we will be free of the infamous
flux corrections (or the unforced climate drift they correct for) in a few years.
If our best information continues to show that we are condemning our distant
desecendants to a radically disrupted environment, while the next generation
or two may get off relatively lightly, what would be the appropriate response?
I'd be interested in hearing from those who don't believe that this is what 
the evidence shows, as well. If the evidence *did* show this, how would you
recommend responding? 
Oh, and by the way, if the evidence *did* show this, how would you expect
fossil fuel interests to respond?
mt
References:
Paleoclimatology / Thomas J. Crowley and Gerald R. North. -- New
              York : Oxford University Press ; Oxford [England] : Clarendon
              Press, c1991.
Climate change 1995 : the science of climate change / edited by
              J.T. Houghton ... [et al.] ; production editor, J.A. Lakeman. --
              Cambridge ; New York, NY, USA : Cambridge University Press, 1996.
Earth in the balance : ecology and the human spirit / Al Gore. --
              Boston : Houghton Mifflin, 1992.
Global physical climatology / Dennis L. Hartmann. -- San Diego :
              Academic Press, 1994.
Physics of climate / Jose P. Peixoto, Abraham H. Oort. -- New York
              : American Institute of Physics, c1992.
S. Manabe & R. Stouffer, 1993: "Century-scale effects of increased atmospheric
	CO2 on the ocean-atmosphere system" _Nature_ V 364 pp 215 ff.

Robert Grumbine wrote:
>The current Great Lakes ice conditions can be found at the US 
>National Ice Center, at http://www.natice.noaa.gov/.
Thanks for posting this address, Bob!  I had been poking around
trying to find this information in a graphical format, tried GLERL and
Ohio State with no luck.  As a note, the data from these charts are
being used in our MAPS 40km experimental system.  If you want to see if
it's doing a decent job with the information, stop by our home page and
check out the real time plots at 
http://www.fsl.noaa.gov/frd-bin/MAPS.homepage.cgi
We have been having some trouble keeping our machine up here, though,
so sometimes the data is old.
Tracy Lorraine Smith  Noting that Lake Erie is frozen over, but none
of the rest are...

Someone sometime ago conducted an experiment to determine how ski's or ice
skates work.
The two theories purposed were:
1.  The Pressure melting theory; Due to the increased pressure on ice, the
melting point is lowered and the skate glides across on the melted layer
of water.  This can be seen from the Clausius-Clapeyron equation.
2.  The Frictional heating theory; Due to the heat generated from friction
between ice and skate, the heat melts some ice, allowing the skate to glid
on the thin sheet of water.
Which theory is correct?  Does the thermal properties of the ski/skate
have anything to do with this?
Mike

Why is the wind chill index independent of the humidity?  Naively, one
might think that more humid air would transfer heat more quickly.
Thank you,
Daniel Lewart
d-lewart@uiuc.edu

what tim e did the sun set last night?

YES...NASA had the Kuiper Airborne Observ. & now
the SOFIA which will be up & flying around 2000
see my  http://www.princeton.edu/~georgel/astronomy.html
and look under spacecrafts/missions
george
Jay Reynolds Freeman (freeman@netcom.com) wrote:
:     One can do interesting astronomy, or at least astronomy-related
: work, from a window seat of a jetliner.  There are several ways to
: detect the curvature of the Earth.  The easiest is to use liquid in
: one of those thin-walled clear cups as a level, and sight across it.
: Even from as little as 40,000 feet, the horizon is very noticeably
: depressed below the horizontal.  If you are lucky enough to have a
: view to the north from mid-temperate latitudes at night, and there is
: an aurora borealis farther to the north, you may be able to see many
: hundreds or thousands of Km of the auroral arc, enough to show that
: its base is curved to follow the curvature of the Earth below.  The
: base will be scores of Km up, so you can see it far beyond the nominal
: horizon.
:     Also, if you are looking obliquely forward toward the setting
: sun, you might get a very long green flash.
: -- 
:    Jay Reynolds Freeman -- freeman@netcom.com -- I speak only for myself.
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
From the mind of:
             George R Lewycky
georgel@princeton.edu or lewycky@soho.ios.com
        Internet Phone:  GeorgeNJ
++++++++++++++++++++++++++++++++++++++++++
  TRY ME:  http://www.princeton.edu/~georgel/
           http://soho.ios.com/~lewycky/
      *    Index of my web pages    *
      * and where they're linked from *
 http://www.princeton.edu/~georgel/toc.html
*********************************************
      An APPLE a day keeps Bill away
        "I'd rather be on Titan !!"
  [ look at my page and you'll see why ]

a bean wrote:
> Does anybody know how the ice samples were dated?
Uh, dinner and a movie?
Sorry. :)

I am looking for tropospheric ozone data for as many locations around
the globe as possible.  Do you know any sources of such data?
Hanna

freeman@netcom.com (Jay Reynolds Freeman) writes:
>> I assume you've heard of the Kuiper Airborne Observatory, an infra-red 
>> telescope looking out of a hole in the side of a 747?
>  Yes, but regrettably, that seat never seems to be available when I do
>business travel.
the 747 is SOFIA, the ``stratospheric observatory for infrared astronomy" 
(i think).  the kuiper is a converted C-141, a military transport jet.
you can get a good look at the kuiper somewhere under the jpl homepage,
i seem to recall.  it's clearly not a 747!  :) 
the kuiper, btw, has been mothballed to provide money for sofia's develop-
ment.  no airborne astronomy for a few more years.
dave
______________________________________________________________________
-David W. Tyler               "It seems you feel our work is not    
-USAF Phillips Laboratory         of benefit to the public."
-Albuquerque, New Mexico                     
-tyler@plk.af.mil                         --Rachel  
************   The views of David Tyler are his own   ****************
and cannot be taken to represent the views of Phillips Laboratory, the 
    U.S. Air Force, the U.S. Government, or WJ Schafer Associates

Question:
Has anyone done any studies on the probability distribution of
annual heating/cooling degree days (or for that matter, average annual 
temperatures) for a given US city? Would it be reasonable to assume that 
the distribution is normal?
I'm pretty sure insurance companies might have done some studies on this, 
but no specific article comes to mind. 
If anyone knows of any specific literature or studies, or even 
consultants that could point me in the right direction, I'd appreciate 
it. 
Joseph Hrgovcic

Hugh Easton wrote:
> If, instead of relating to CO2 level and global temperature, the Vostok
> ice core data set showed the level of a chemical in the diet and the
> incidence of cancer, I do not think there would be much argument that the
> chemical is carcinogenic. Or that it should be banned if a substantial
> percentage of the human race were shown to be at risk from it.
Leaving aside the question of exactly what the Vostok data acutally
shows, there is a problem with this.
The notion that a chemical causes cancer is not going to be accepted
solely on the basis of a statistical correlation between that
chemical and cancer cases.  For example, some chemicals are indicators
that cancer is present rather than cancer causing agents. What is
required is a mechanism for the cancer production and experiments
to verify that this mechanism exists and operates in humans. Such
are quite amazingly well documented and verified for a variety of
chemicals in that these chemicals produce DNA damage of exactly
the type which tends to lead to cancer.  Such evidence constitutes
the proverbial smoking gun, and such evidence is strengthed by
correlations between chemical exposure and cancer rates.
In the absence of such mechanisms, one might well be lead to
believe that it was holding the paper ciggs were wrapped in
that produced the cancer.  Or uncrinkling that silly plastic
wrap on every package. Or reading the health warning. Or
standing in front of vending machines. Or any number of other
things that are correlated with cancer because they are
correlated with ciggarettes.  Without a mechanism, cause and
effect are difficult to unravel.
Suppose that your data shows CO2 levels are driven by temperature
rather than the other way around.  You mention losing correlations
if you shift the data by 1000 years.  Suppose the CO2 levels are
trailing temperature rather than leading it. Maybe various activity
of organisms that occurs at higher temperatures produces it.
Maybe CO2 does not dissolve in oceans as readily at higher temps.
Maybe the process of CO2 forming calcium carbonate does not work
as fast at higher temperatures because CO2 does not dissolve as
readily.
Or maybe the two are accidentally correlated. Maybe ocean currents
get messed up at some temperature threshold, and CO2 deposits on
ocean floors get turned off.
Good science would require a mechanism to explain a correlation
before it was considered evidence of anything. The slight
insulation effect of CO2 is clearly not, in and of itself by
itself, enough to account for the temperature differences
projected.
-- 
Standard disclaimers apply.
I don't buy from people who advertise by e-mail.
I don't buy from their ISPs.
Dan Evens

Glitter910 wrote:
> 
> what tim e did the sun set last night?
   At dusk or never depending on where you live.
-- 
                                 Bill
+--------------------------------------------------------------+
¦If everything possible, then it is impossible to know anything¦
¦with a substantial degree of confidence worth building upon.  ¦
+--------------------------------------------------------------+

I can't find the original messagel, but this is to Matt. Thanks for your
responce. I'll get together some question to ask, since the assignment is
to interview an expert. I need answers such as: How tornadoes can be
studied, what makes them up, guesses on how they form, and what they
exactly do in their profession. Please respond by posting, as my lording
brother controls the internet and erases my mail :( He's not that mean. I
just made him sound mean>)
Nick

Neil Flood wrote:
> 
> Dear met gurus,
> 
> someone (who ought to know) just told me that you don't get hailstorms
> in the tropics. Is this so ? and if so why ? The obvious answer is that
> it is too warm, but that sounds a little trite.
> 
> many thanks
> 
> Neil
> 
> --
> ------------------------------------------------------------------------------
> Neil Flood                            e-mail: neilf@dpi.qld.gov.au
> Drought Research Unit
> QLD Dept of Natural Resources (formerly Dept of Primary Industries)
> AUSTRALIA
> ------------------------------------------------------------------------------
Warm is the right answer, but probably not in the ambient temperature
sense you may be thinking.  Tropical thunderstorms don't have the cold
updrafts associated with the mid-latitude thunderstorms.  It's these
cold (violent) updrafts that give the hailstone the rides up and down in
the storm.  Tropical thunderstorms, therefore, don't have the turbulence
associated with mid-latitude thunderstorms.

trv@Hiwaay.net wrote:
>Just curious if anyone has missed the GREAT model images that Duke Power
>/UNCC had and have now been removed!! Just when things were getting
>great on the Net soneone pulls the plug.I realize how much some sites
>take on hits per day but removing great data such as these only hurts
>the cause out here in WxLAND and without other universities taking on
>the demand that people out here on the Net want, where is the future of
>weather data going from this point?? These are great days for myself as
>well as others I'm sure, who seriously want and need the free data that
>exsist out there and hope others will voice their concerns over these
>matters here..UNCC/Duke..we really miss those images!!:)But thanks
>guy's!
>						Thanks
>						Tim Vickery
I am looking into a couple of solutions to putting out the data,
possible on an external server off the Duke Power network. The problem
is the large amount of data that is sent to the server, and the number
of hits it receives.  The only way it may work, is some type of
subscription service to recover the network/server cost. I am not sure
that people will be willing to pay for what is already available on
the 'net'... But at the same time I can't expect to continue using
corporate network resources without some way to recover the expenses.
If anyone has any ideas let me know...
Mike Dross
mike@wxlab.dukepower.com

Mike,
The beauty of what you did was the fine tuning of the WXP parameters. 
Would you be willing to allow someone else (most likely a college or
university) to run WXP using your settings?  There are a number of
schools that display model outputs, but with nowhere near the visual
impact.
What kind of resources (computing power and bandwidth) would be
necessary to replicate the Duke Power portion of the maps UNCC hosted?
We really do miss them.
Geoff
-- 
and then there's my home page...
http://www.netcom.com/~gfox

Is there a website with all the ICAO four letter weather
station codes (e.g. FAJS = Johannesburg) ?
Thanks,
Klaas
-------------------==== Posted via Deja News ====-----------------------
      http://www.dejanews.com/     Search, Read, Post to Usenet

Does anyone know if there is a site that gives a current jpg of
lightning strikes in the U.S.
Thanks

Is there any where that records the number of earthquakes per century?

Hi
I used to work for British Airways, and there was a 
regular 'tourist' trip on concorde. One of the thrills
was the pilot would bank hard at about 55,000 Ft and 
out of the windows the sky appears blackish and stars 
can be seen.
Alun

Hi!
Does anybody a reference where I can get simple climate datas as
temperature and precipitation ... of the most popular stations whole
over the world??
THANKS
Alex

In article <5c8lmn$q@vixen.cso.uiuc.edu>, d-lewart@uiuc.edu (Daniel S. Lewart) wrote:
>Why is the wind chill index independent of the humidity?  Naively, one
>might think that more humid air would transfer heat more quickly.
Dry air speeds sweat evaporation and thus removes heat faster. That principle 
underlies the psychrometer (a matched pair of dry- and wet-bulb thermometers). 
However, that effect is quite small in cold weather.
Sandy
Oakville, Ontario

Ron Moniz  writes:
> I am a wx observer and Skywarn spotter on a ham radio wx net.
> On one of our nets a question about a "gravity wave" was brought
> up after one of our wx observers heard the term used by a local
> television meterologist after a wx system brought unusually high
> tides and less than predicted rain and snowfall. The local NWS
> office is looking for barometric pressure trends from observers
> from that particular event that night.
> Could someone briefly describe what a gravity wave is or where one 
> might find more info on the subject.
> 
FWIW here are two articles posted to sci.geo.meteorology
-- 
	______                                    ______ 
	___/ /_______________________________________/ /_
	/_  __//_____//_Jacques_//_Marcoux_//_____/_  __/
	 /_/                                       /_/   
	       jmarcoux@ec.gc.ca 514.421.4794
From: mbentley@unlgrad1.unl.edu (mace bentley)
Newsgroups: sci.geo.meteorology
Subject: Re: Gravity Wave ?
Date: 24 Jul 1995 10:06:37 GMT
Organization: University of Nebraska--Lincoln	
Lines: 47
References: <3uunao$63q@widomaker.widomaker.com>
NNTP-Posting-Host: unlgrad1.unl.edu
X-Newsreader: TIN [version 1.2 PL2]
Hank Bastian (hankmb@widomaker.com) wrote:
: In some recent articles dealing with storms,  I have seen the term
: gravity wave mentioned.  The articles have failed to describe the
: term.  I would like to know what a gravity wave is, how it works, and
: its significance.   Thanks.   
: 		Hank
A gravity wave is simply a density surge, or wave of air being of a 
different density than the surrounding air.  The wave moves and is 
"produced" by hydrostatic pressure forces.  There are several 
mechanisms which force gravity waves: orographics and convection are
two of the most common.  When neutral or negatively buoyant air is 
forced over the Rockies, this air will oscillate above and 
below its equilibrium level.  These oscillations, which are due to 
gravity and its effects on density discontinuities of the air, are 
gravity waves.  In thunderstorms, two main mechanisms can force 
gravity waves.  One is the updraft, which can once again displace air 
well over its equilibrium level and also produce an overshooting top. 
Stable air flowing up and over the overshooting top along with air from the 
updraft displaced well above its equilibrium level can force gravity 
waves. In high resolution visible satellite imagery one can sometimes
see oscillations downwind of the overshooting top.  These gravity waves 
are typically produced by the beforementioned processes.  Another "forcing" 
mechanism is through convective excitation.  This is due, in part, to 
the very large amounts of latent heat release and absorption that occur 
within mature thunderstorms and thunderstorm complexes.  This can produce 
tight density/buoyancy gradients within the thunderstorm.
Depending upon the structure of the atmosphere where they form, 
gravity waves can be ducted and sustained over very long distances.  
These waves can act as a convergent focus, much like a frontal 
boundary (another type of density discontinuity), for convection.
They can also occasionally produce very high winds and severe 
clear-air turbulence on their own as they move, sometimes at high 
rates of speed (60-80 knots), through the atmosphere.  Gravity waves  
can sometimes be found through isentropic cross-sections and/or 
pressure surges at the suface.  They are predominanatly a 
mesoscale phenomena, so detection can be difficult.
I hope this clears things up for you - BTW I'm by no means an expert 
on this - if any other scientists have better explanations please 
contribute!
Mace Bentley
Program in Meteorology
University of Nebraska-Lincoln
From: mbentley@unlgrad1.unl.edu (mace bentley)
Newsgroups: sci.geo.meteorology
Subject: Re: Gravity Wave ?
Date: 24 Jul 1995 10:06:37 GMT
Organization: University of Nebraska--Lincoln	
Lines: 47
References: <3uunao$63q@widomaker.widomaker.com>
NNTP-Posting-Host: unlgrad1.unl.edu
X-Newsreader: TIN [version 1.2 PL2]
Hank Bastian (hankmb@widomaker.com) wrote:
: In some recent articles dealing with storms,  I have seen the term
: gravity wave mentioned.  The articles have failed to describe the
: term.  I would like to know what a gravity wave is, how it works, and
: its significance.   Thanks.   
: 		Hank
A gravity wave is simply a density surge, or wave of air being of a 
different density than the surrounding air.  The wave moves and is 
"produced" by hydrostatic pressure forces.  There are several 
mechanisms which force gravity waves: orographics and convection are
two of the most common.  When neutral or negatively buoyant air is 
forced over the Rockies, this air will oscillate above and 
below its equilibrium level.  These oscillations, which are due to 
gravity and its effects on density discontinuities of the air, are 
gravity waves.  In thunderstorms, two main mechanisms can force 
gravity waves.  One is the updraft, which can once again displace air 
well over its equilibrium level and also produce an overshooting top. 
Stable air flowing up and over the overshooting top along with air from the 
updraft displaced well above its equilibrium level can force gravity 
waves. In high resolution visible satellite imagery one can sometimes
see oscillations downwind of the overshooting top.  These gravity waves 
are typically produced by the beforementioned processes.  Another "forcing" 
mechanism is through convective excitation.  This is due, in part, to 
the very large amounts of latent heat release and absorption that occur 
within mature thunderstorms and thunderstorm complexes.  This can produce 
tight density/buoyancy gradients within the thunderstorm.
Depending upon the structure of the atmosphere where they form, 
gravity waves can be ducted and sustained over very long distances.  
These waves can act as a convergent focus, much like a frontal 
boundary (another type of density discontinuity), for convection.
They can also occasionally produce very high winds and severe 
clear-air turbulence on their own as they move, sometimes at high 
rates of speed (60-80 knots), through the atmosphere.  Gravity waves  
can sometimes be found through isentropic cross-sections and/or 
pressure surges at the suface.  They are predominanatly a 
mesoscale phenomena, so detection can be difficult.
I hope this clears things up for you - BTW I'm by no means an expert 
on this - if any other scientists have better explanations please 
contribute!
Mace Bentley
Program in Meteorology
University of Nebraska-Lincoln

Hi, 
I would recommend to get the programm called alw203.* at your
nearest ftp-site. This program will give you the sunrise and sunset
time plus some other things.
You can then make a chart out of it.
Bye

hh  wrote in article <5c8o7v$6he@uuneo.neosoft.com>...
> Question:
> 
> Has anyone done any studies on the probability distribution of
> annual heating/cooling degree days (or for that matter, average annual 
> temperatures) for a given US city? Would it be reasonable to assume that 
> the distribution is normal?
     I've looked at some monthly mean temperature figures our "official"
station here in Duluth, Minnesota from 1956 to 1990 and calculated standard
deviation for the mean temperature each month.  I live in a part of Duluth
closer to Lake Superior which sees different temperature patterns, but with
only seven years of data so far, I haven't made similar calculations.  But,
here is some of what I found for the Duluth International Airport over that
35-year span.  All figures are in degrees F.
     Month		Mean temp (1956-1990)		Standard deviation
January			7.3				5.74
February		12.1				5.24			
March			24.1				4.64	
April			38.5				3.30
May			50.6				3.04
June			59.2				2.34
July			65.5				2.43
August			63.3				2.61
September		54.1				2.60
October			43.8				3.56
November		28.2				3.73
December		13.2				5.45
     Not surprisingly, the largest standard deviation is in January, when
the temperature gradient across North America is the tightest, and standard
deviation is least in summer.  It explains why a January with a mean
temperature of 11.3 degrees F, 4 degrees above normal (about 0.75 standard
deviations) is slightly above normal, but a June with a mean temperature of
63.2 degrees F, also 4 degrees above normal (but almost 2 standard
deviations above normal) is much above normal.  The same applies to daily
high and low temperatures, although those standard deviations are larger
than those for monthly means.  
     As far as outliers, the extremes for January during this period were
18.7 degrees in January 1990 (11.4 degrees above normal) and -3.2 degrees
in January 1982 (10.5 degrees below normal).  July was much less variable,
with extremes of 70.0 degrees (4.5 degrees above normal in July 1988) to
60.8 degrees (4.7 degrees below normal in July 1962).  
    Some factors which will affect the distribution and standard deviation
are:
-Latitude--at higher latitudes, generally standard deviation will increase.
 Even Fairbanks, Alaska has had a January which averaged 18.0 degrees F
(January 1981), almost as warm as Duluth's warmest January.  Duluth's
latitude is 46.8 degrees N, Fairbanks, Alaska is at almost 65 degrees N.
-A continental location will see higher standard deviation.  A fascinating
way to look at this is to compare cities' overall temperature extremes. 
Eureka, California and Peoria, Illinois are both located at 40.8 degrees N
latitude.  Peoria's (located far from large bodies of water and far enough
from Lake Michigan to receive little if any effect from the lake on its
climate) all-time record high and low are 103 and -25, a difference of 128
degrees.  Eureka, on the Pacific Ocean, has an all time record high and
record low of 87 and 21, a difference of only 66 degrees.  Records in
Eureka go all the way back to 1910, yet over this 87-year period it has
maintained remarkably consistent temperatures due to the proximity of the
Pacific.  The all-time record high for the month of July in Eureka is only
76 degrees, certainly one of the coolest in the Northern Hemisphere.
-Elevation also plays a role, with generally greater temperature
fluctuations at higher elevation.
     Lake Superior (and the Great Lakes in general) can affect temperature
distribution locally.  One example is Sault Ste. Marie, Michigan.  In Sault
Ste. Marie, only about one year in 30 has a mean temperature more than 1.5
degrees above or below its annual mean temperature of 39.5 degrees.  With
three of the five Great Lakes within 50 miles of Sault Ste. Marie, they do
a reliable job of moderating local temperatures.  Also, when the early part
of the year in Sault Ste. Marie is cold, fall tends to be warm to
compensate, and vice versa.
   Going back to the original question in the post, I would say that the
distribution is somewhat close to normal in many locations--especially
lower elevation, mid-latitude continental locations--but there are some
where it is definitely not true.  Any climate with a considerable water
influence (U.S. west coast, western Lower Michigan, or my neighborhood in
Duluth as three examples) does not have as clear a normal distribution. 
From my records I've taken, my coldest temperatures are in January but the
warmest month is August, not July as it is in more continental locations. 
Lake Superior and the rest of the Great Lakes reach their peak temps in
late August, which is when my warmest average readings are.  Thus, temps
fall relatively quickly over 5 months to their January lows but climb to
their highs more gradually over a 7-month period.  Many stations in
Michigan are coldest in February because the Great Lakes are still mostly
open in January, holding up temps and increasing the chances of lake-effect
snow.
Jody Aho
jaho@cp.duluth.mn.us

purdees@aol.com (Purdees) wrote:
>I need a chart of times of sunrises and sunsets for the next few weeks.
>Where can I find it? 
Try http://riemann.usno.navy.mil/AA/data/online.html/
Input your location and desired date(s) and you'll get your info in 
tabular, not chart, form.  If your location is not in the database, 
pick a nearby larger town.
--Rowland