No antennae radiate all the power fed to them!
 

On 11/3/2014 3:36 AM, Lostgallifreyan wrote:
rickman wrote in :

Recorded temperatures have always set new records. Just considering one
location, there are 365 days in a year and so 730 high and low records
to test. We have been recording temperatures for roughly 200 years.
What are the chances we *won't* set a new record for one of those dates
in a given year?


True, it's no great deal intself. And given the Maunder Minimum soem big
excursions can be expected, especially as the sun isn't following its usual
11-year pattern. On the other hand I remember people asking me in 1983 about
glonal warming, and me insisting that it did not just mean warmer, but
wetter, stormier, as well. There's no doubt that compared to thiry years ago
this has happened across most of thwe world.

There is tons of doubt. Considering your "impression" of what you have
heard about is not science.


For a real balance of 'records',
we need to know how often the record for quietest, or closest approach to
average, conditions occured, and I have never heard the like. :) Generally,
if news is not exciting, it is not considered as news. Also, even when we had
unusual cold recently, it is arguable that climate conditions don't cause a
strong enough gradient to keep a strong division of temperature with
lattitude, and similar things can be said about the wandering of the jet
stream. Too many things look new, an the rate of broken records is increasing
when it ought to be decreasing if things were generally stable.

I think you are talking through your hat. Let the scientists analyze
the data and come up with facts.

--

Rick

No antennae radiate all the power fed to them!
 

rickman wrote in :

I think you are talking through your hat. Let the scientists analyze
the data and come up with facts.


I do. Those are where I get that impression. Many people ignore them, but
they will keep saying it.

No antennae radiate all the power fed to them!
 

On 11/3/2014 4:19 AM, Lostgallifreyan wrote:
rickman wrote in :

Hmmm... All things emit energy according to their temperature and their
surface emissivity. All things also absorb energy according to their
surface emissivity. Both processes are going on at all times. So an
object loses or gains heat depending on its temperature and the
temperature of the environment. That delta temperature sets the rate
along with the surface emissivity.


Ok, that works for me. I guess the rate of change is exponential just as
energy loss in a fading note from a stretched string, roughly reaching
equilibrium when it can't lose more energy to ambient conditions.

Equilibrium is when the temperatures are equal. Of course this is a bit
of a cyclic definition because of how we define temperature. Still,
that is the point, equilibrium means equal heat exchange in both
directions.


About warming of superconductors out there, I may be wildly underestimating
the effect of a difference of 77K. What's I'd thought of was that if a
supeconductor can only operate at a very low temperature, its thermal
emission will be low; perhaps so low that it might take very little input
(from whatever, I know not what, and especially so if its emissivity is high
making absorbtion easy) to balance that and stop it staying cold enough. My
difficulty comes from not being sure whether a difference of 77K means the
same thing at cryogenic temperatures as it does around room temperature,
because it's not an infinite continuum of temperature.

Trouble is you don't really think like a scientist or engineer.
Temperature *is* a continuous function and each degree is the same. If
you want to understand it, look at the math. There are no step
functions in the equations for heat exchange. Remember what I wrote,
"delta temperature" determines the rate of heat exchange. Nowhere did I
say depending on if you are in "cryogenic" ranges. The equations don't
know what we consider "cryogenic". It takes the same amount of heat to
raise a substance 1 degree at 77 °K as it does at room temperature.
Also remember that I only picked 77 °K as a convenience (boiling point
of N2) as we know there are a number of superconductors with their
transition temperature well above that. The key is "well above".


I was thinking that
because it is so cold, that small amounts of heat lost from other equipment,
might find their way to a superconductor and cause bother in the absence of
forced cooling. I can't really imagine any use of superconductors in space
that would not include the risk of local heat sources.

An antenna is also subject to EMC. It is not uncommon to mount them
clear of the rest of the craft. It's easier to insulate them from heat
sources than it is to isolate them from EMC from the rest of the craft.

--

Rick

No antennae radiate all the power fed to them!
 

rickman wrote in :

Trouble is you don't really think like a scientist or engineer.


I'm neither. I managed to build a phase modulation synthesiser despite that.
I get by. :) And I usually do that by being willing to go beyond my 'comfort
zone'. How many other people who are not engineers or scientists do you see
posting around here?

No antennae radiate all the power fed to them!
 

"Lostgallifreyan" wrote in message
. ..
How many other people who are not engineers or scientists do you see
posting around here?

In discussions about short antennae, quite a few from Yankland.

No antennae radiate all the power fed to them!
 

rickman wrote in :

It takes the same amount of heat to
raise a substance 1 degree at 77 °K as it does at room temperature.

Ok, but when I read (or hear on BBC radio science programs) that it takes FAR
more effort (energy) to pump from 2K to 1K than it does from 300K to 299K,
what am I supposed to make of that given what you just said?

No antennae radiate all the power fed to them!
 

On Sunday, November 2, 2014 6:51:50 PM UTC-6, Jerry Stuckle wrote:

Which means it rolls once per orbit. Otherwise it wouldn't be able to
keep the same side facing the earth.



I'll take you all's word for it.. I was pondering it as you
would a matchbox car rolling across a globe.. ??
If it's rolling, it must be real slow about it, as it's not
really detectable on the cameras.

No antennae radiate all the power fed to them!
 

On 11/3/2014 3:36 AM, Lostgallifreyan wrote:
rickman wrote in :

Recorded temperatures have always set new records. Just considering one
location, there are 365 days in a year and so 730 high and low records
to test. We have been recording temperatures for roughly 200 years.
What are the chances we *won't* set a new record for one of those dates
in a given year?


True, it's no great deal intself. And given the Maunder Minimum soem big
excursions can be expected, especially as the sun isn't following its usual
11-year pattern. On the other hand I remember people asking me in 1983 about
glonal warming, and me insisting that it did not just mean warmer, but
wetter, stormier, as well. There's no doubt that compared to thiry years ago
this has happened across most of thwe world. For a real balance of 'records',
we need to know how often the record for quietest, or closest approach to
average, conditions occured, and I have never heard the like. :) Generally,
if news is not exciting, it is not considered as news. Also, even when we had
unusual cold recently, it is arguable that climate conditions don't cause a
strong enough gradient to keep a strong division of temperature with
lattitude, and similar things can be said about the wandering of the jet
stream. Too many things look new, an the rate of broken records is increasing
when it ought to be decreasing if things were generally stable.


The problem is the Earth's climate is a very complex system. You can't
take a small area and project what's happening world-wide; things are
too interconnected.

This would be like taking one street in a big city and count cars going
by. If the number of cars goes down, you can't say "traffic in the city
is lighter" because there might have been an occurrence such as an
accident on a feeder road which is blocking up traffic.

At the same time, if the number of cars increases, you can't say
"traffic is heavier" - there might have been an accident in another
location and people are getting around it by using this street. It's
all tied together.

A perfect example with the weather is last winter. North America had
one of the coldest winters in recent years (due to the polar vortex
moving our way). But Europe and Asia had one of the warmest winters in
recent years; world-wide the average temperature increased.

The last figure I heard was that 95% of climatologists (people who
should know better than anyone else) agree that global warming is
occurring, as indicated by world-wide average temperatures. There is
still debate, even amongst them, how much man is responsible for this
warming. But still the vast majority believe that man is responsible
for at least some of the warming.

So, as rickman pointed out, (paraphrasing) with only 200 or so years of
tracking temperatures (even less than that in much of the Americas),
there is almost a certainty some locations will report record highs, and
some locations will report record lows.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

No antennae radiate all the power fed to them!
 

On Monday, November 3, 2014 11:05:11 AM UTC-6, gareth wrote:
"Lostgallifreyan" wrote in message
. ..
How many other people who are not engineers or scientists do you see
posting around here?

In discussions about short antennae, quite a few from Yankland.

I'm just a regular ole ham here. Never studied any of this stuff
in school, and don't work in any related field.
Everything I've learned, I learned on my own. Mainly from books,
of which I have several. I trust good textbooks a lot more than I
trust usenet jibber jabber. Usenet jibber jabber is only as good
as the qualifications of the one jabbering. Some info is good, some
is bad, and some is pure unadulterated bafflegab.

No antennae radiate all the power fed to them!