Why do you cool a telescope?

Paul Schlyter wrote:

Las Vegas is a big city in a small desert (at least it's small
compared to e.g. the Arabian peninsula). Cities produce their own
heat and often have a temperature different from the surrounding
countryside..... that's why e.g. NYC is so much hotter than its
surroundings, particularly at night. I suppose the same is valid for
Las Vegas as well.

Oh, it's not so big. And the desert is tens, if not hundreds of
miles around. Anyway, even if it was hotter in the city itself, it
would be 2-3 degrees at most.

Also: Las Vegas isn't the best observing location for another major
reason: ...l.i.g.h.t...p.o.l.l.u.t.i.o.n...

Around midninght it was still above 90F - incredibly hot for me.

...but 90F is still not 110F --- despite the heat from the city.....

I don't live there (thanks God!) so I don't know - maybe sometimes
it's even hotter? You know, I was in the hotel room and sometime
around 10pm I decided to take a walk outside. Just opened the door
and it was feeling like peering into an oven.

(I don't even want to remember what was during the day! How
these guys survive over there?!)

Air conditioning.

Yeah, but the trip of 20 yards from the car to the hotel room was
enough to make me thirsty and in urgent need of a cold shower, :-)
I can imagine following report in the newspaper - "... and 10 people
died on the spot when the AC in their car failed ..." :-)

Maybe given some tome to get used to the heat...

- Alex

Have you ever been in a desert?
=20
The desert cools off rapidly at night, and can even approach freezing
temperatures towards dawn. It will very unlikely be 110-111 deg F
at night in the desert.
=20

I have to ask have YOU ever been in a desert?? Yesterday's high in Palm =
Springs was 109=B0. The overnight low was 82=B0. Some nights it never =
gets below 90=B0. In the winter it will occasionally freeze overnight.

-Florian

In article ,
Alexander Avtanski wrote:

Paul Schlyter wrote:

Las Vegas is a big city in a small desert (at least it's small
compared to e.g. the Arabian peninsula). Cities produce their own
heat and often have a temperature different from the surrounding
countryside..... that's why e.g. NYC is so much hotter than its
surroundings, particularly at night. I suppose the same is valid for
Las Vegas as well.

Oh, it's not so big. And the desert is tens, if not hundreds of
miles around.

....which is very small compared to e.g. the Sahara desert....

Anyway, even if it was hotter in the city itself, it
would be 2-3 degrees at most.

I looked up Las Vegas on a map, and noticed you have the Rocky
Mountains nearby. So you may have much more clouds than the
typical desert. And if it's hot during the day, and cloudy at
night, then of course the heat won't radiate away very well.

But 110F at night still sounds a bit too much....

Also: Las Vegas isn't the best observing location for another major
reason: ...l.i.g.h.t...p.o.l.l.u.t.i.o.n...

Around midninght it was still above 90F - incredibly hot for me.

...but 90F is still not 110F --- despite the heat from the city.....

I don't live there (thanks God!) so I don't know - maybe sometimes
it's even hotter? You know, I was in the hotel room and sometime
around 10pm I decided to take a walk outside. Just opened the door
and it was feeling like peering into an oven.

When I visited Mauritanina in 1973 to view the total solar eclipse (7
min totality max; I got 6 min totality), we had some 50C (that's
120+F) during daytime. But at night it cooled down to perhaps 20C
(that's 68F) - a quite comfortable temperature which encouraged you
to take a walk outside. During totality we had 32C (that's 90F).
Air conditioning? Forget that -- we lived in tents!!!!

(I don't even want to remember what was during the day! How
these guys survive over there?!)

Air conditioning.

Yeah, but the trip of 20 yards from the car to the hotel room was
enough to make me thirsty and in urgent need of a cold shower, :-)
I can imagine following report in the newspaper - "... and 10 people
died on the spot when the AC in their car failed ..." :-)

I thought car batteries provide DC and not AC..... :-)

Maybe given some tome to get used to the heat...

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

In article ,
Florian wrote:

Have you ever been in a desert?

The desert cools off rapidly at night, and can even approach freezing
temperatures towards dawn. It will very unlikely be 110-111 deg F
at night in the desert.

I have to ask have YOU ever been in a desert?? Yesterday's high in
Palm Springs was 109_deg.

Palm Springs? A typical desert has neither palms nor springs.... g

The overnight low was 82_deg. Some nights it never gets below 90_deg.

....and will it EVER get as hot as 110F at night there ????

In the winter it will occasionally freeze overnight.

In 1973 I visited Mauritanina to view the total solar eclipse (7
min totality max; I got 6 min totality). If you look up Mauritania
on a world map, you'll see that it resides in the Sahara desert.

At first we stayed in Nouakchott (the capital of Mauritania), which
is near the ocean. That made the temperature bearable. But the day
before totality, we travelled away from the ocean and into the zone
of totality, to Akjoujt. There we had some 50C (that's 120+F) during
daytime. But at night it cooled down to perhaps 20C (that's 68F) - a
quite comfortable temperature which encouraged you to take a walk
outside. During totality we had 32C (that's 90F). Air conditioning?
Forget that -- we lived in tents!!!!

After I had returned home, it took almost a week before I had washed
away that orange-ish very fine sand from my hair.....

In northern colder climates you'll get a lot of snow on the roads
in winter, so you'll have to drive cars which plow away the snow
from the roads. In Nouakchott they have a similar problem, but
all year round: they'll have to plow away SAND from the roads
regularly..... there are sand storms there quite often, which moves
around large amounts of sand in an uncontrollable way.....
Do you have similar problems in Palm Springs or Las Vegas? g


Apparently, the North American "deserts" are quite different from
the deserts in Sahara and on the Arabian peninsula.... so I'd like
to ask you if YOU have been in a desert? And then I mean a _real_
desert, not a "desert" with palms and springs and casinos....

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

Apparently, the North American "deserts" are quite different from
the deserts in Sahara and on the Arabian peninsula.... so I'd like
to ask you if YOU have been in a desert? And then I mean a _real_
desert, not a "desert" with palms and springs and casinos....


Palm Springs is on the western edge of the Sonoran desert. It's desert =
by all accepted definitions of the term. I live in a desert no matter if =
you agree or not.=20

-Florian

On Thu, 10 Jul 2003 20:47:57 +0000 (UTC), (Paul Schlyter) wrote:

Las Vegas is a big city in a small desert (at least it's small
compared to e.g. the Arabian peninsula). Cities produce their own
heat and often have a temperature different from the surrounding
countryside..... that's why e.g. NYC is so much hotter than its
surroundings, particularly at night. I suppose the same is valid for
Las Vegas as well.

Trust me, Paul, the heat in the Nevada desert has nothing to do with the
proximity of the city of Las Vegas. There are many deserts in the United States
that remain very hot all night long.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Chris L Peterson wrote:

On Thu, 10 Jul 2003 20:47:57 +0000 (UTC), (Paul Schlyter) wrote:

Las Vegas is a big city in a small desert (at least it's small
compared to e.g. the Arabian peninsula). Cities produce their own
heat and often have a temperature different from the surrounding
countryside..... that's why e.g. NYC is so much hotter than its
surroundings, particularly at night. I suppose the same is valid for
Las Vegas as well.

Trust me, Paul, the heat in the Nevada desert has nothing to do with the
proximity of the city of Las Vegas. There are many deserts in the United States
that remain very hot all night long.


Ripped off from: Mike Davis

House of Cards
Las Vegas: Too many people in the wrong place,
celebrating waste
as a way of life.


"The combination of waste heat and vast
paved surfaces transforms the city into a
scorching "heat island" whose
nightly temperatures are frequently 5 to 10
degrees hotter than the
surrounding desert. "

here is another one that talks about heat islands desert
http://search.csmonitor.com/durable/...9/23/p16s1.htm

or the heat island group
http://eetd.lbl.gov/HeatIsland/LEARN/

and one more
http://www.snipsmag.com/CDA/ArticleI...,92239,00.html

So how far does the plume from a heat island extend ? depends on the wind speed,
RH, soil conditions
and the like . I have looked at some model out puts and you can see the Plume move
down wind with time.
At night the stability of the atmosphere changes and the plume can form an
inversion. I have no idea
of how far it extends myself.

Dan

In article ,
John Steinberg wrote:

Paul Schlyter wrote:

Apparently, the North American "deserts" are quite different from
the deserts in Sahara and on the Arabian peninsula.... so I'd like
to ask you if YOU have been in a desert? And then I mean a _real_
desert, not a "desert" with palms and springs and casinos....

Good grief! Now he's even bashing our deserts! Is there no end to
your anti-Americanism?

WHAT?????

Are you having a severe superiority complex, or something? Do you
really require your country to be the BIGGEST and BEST on ABSOLUTELY
EVERYTHING ??? Sorry, but you'll just have to face the fact that the
largest deserts of the world resides outside the US -- and saying so
is merely stating a fact. Claiming it's "anti-Americanism" is just
ridiculous !!!!!!!!!!!!!!

BTW I'll readily admit that the deserts in Sweden are even smaller
than the deserts in the US .... as a matter of fact they're
non-existent, since we don't have any deserts here. So by your logic
I've now been bashing my own country Sweden even more, and thus I
have devoted myself to endless anti-Swedishism.... .... by your
logic, that is, not by my logic...... evil grin


Tell you what, we'll start a fund drive to have you fly over and spend
two weeks in a tent in Death Valley. Then will we'll see what you
think of our deserts.

Probably easier to endure than the middle of the Sahara desert in,
say, southernmost Algeria..... I would of course want to try them
both before passing any definite judgement.


P.S. Saab is owned by? Volvo is owned by? Neener, neener, neener.

I know these car companies nowadays are owned by Ford and General
Motors. And I couldn't care less .... to me, a car is a means of
transportation, not a means to try to boast my ego....

BTW the US cars by which you drive into Death Valley would most
likely fail if you tried to use them to drive across the Sahara
desert... sure, they could probably stand the heat, but the sand
which creeps in the machinery everywhere would make them fail perhaps
after a week or two....

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

In article ,
Florian wrote:

Apparently, the North American "deserts" are quite different from
the deserts in Sahara and on the Arabian peninsula.... so I'd like
to ask you if YOU have been in a desert? And then I mean a _real_
desert, not a "desert" with palms and springs and casinos....

Palm Springs is on the western edge of the Sonoran desert. It's desert
by all accepted definitions of the term. I live in a desert no matter
if you agree or not.

OK, I've never been there so I you can tell that better than me. But
why is the city (town? village?) called Palm Springs?

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

Palms and springs occur in deserts. Your idea that a desert has to be
nothing but sand dunes is based on one experience in one desert. And
it's wrong. I've been to the desert of the Arabian Peninsula that you
mentioned and guess what? No sand dunes but there are palms and
springs. But different than the Sonoran Desert of the US and Mexico --
which despite your ignorance of the matter is one of the great deserts
of the world. The Gobi is different still, as is Antarctica and the
summit of Mount Everest, both of which are deserts.

If I were to use your methods then based on your comments I might
generalize and conclude that all Swedes are ignorant and unable to learn
when corrected by knowledgeable people. But, fortunately, I don't
follow that pattern -- and I've met very knowledgeable and reasonable
Swedes.

Mike Simmons

Paul Schlyter wrote:

In article ,
Florian wrote:

Have you ever been in a desert?

The desert cools off rapidly at night, and can even approach freezing
temperatures towards dawn. It will very unlikely be 110-111 deg F
at night in the desert.

I have to ask have YOU ever been in a desert?? Yesterday's high in
Palm Springs was 109_deg.

Palm Springs? A typical desert has neither palms nor springs.... g

The overnight low was 82_deg. Some nights it never gets below 90_deg.

...and will it EVER get as hot as 110F at night there ????

In the winter it will occasionally freeze overnight.

In 1973 I visited Mauritanina to view the total solar eclipse (7
min totality max; I got 6 min totality). If you look up Mauritania
on a world map, you'll see that it resides in the Sahara desert.

At first we stayed in Nouakchott (the capital of Mauritania), which
is near the ocean. That made the temperature bearable. But the day
before totality, we travelled away from the ocean and into the zone
of totality, to Akjoujt. There we had some 50C (that's 120+F) during
daytime. But at night it cooled down to perhaps 20C (that's 68F) - a
quite comfortable temperature which encouraged you to take a walk
outside. During totality we had 32C (that's 90F). Air conditioning?
Forget that -- we lived in tents!!!!

After I had returned home, it took almost a week before I had washed
away that orange-ish very fine sand from my hair.....

In northern colder climates you'll get a lot of snow on the roads
in winter, so you'll have to drive cars which plow away the snow
from the roads. In Nouakchott they have a similar problem, but
all year round: they'll have to plow away SAND from the roads
regularly..... there are sand storms there quite often, which moves
around large amounts of sand in an uncontrollable way.....
Do you have similar problems in Palm Springs or Las Vegas? g


Apparently, the North American "deserts" are quite different from
the deserts in Sahara and on the Arabian peninsula.... so I'd like
to ask you if YOU have been in a desert? And then I mean a _real_
desert, not a "desert" with palms and springs and casinos....

--
----------------------------------------------------------------

Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN

e-mail: pausch at stockholm dot bostream dot se

WWW: http://www.stjarnhimlen.se/

http://home.tiscali.se/pausch/