I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with finding
the height of the balloon.

The control tower of this airfield was equipped with two pillars to which
theodolites could be attached/mounted. Apparently, these were used to
determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I can
see) that you need the horizontal distance to the balloon as well as the
angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.

"Brian Salt" wrote in message
k.co.uk...

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with finding
the height of the balloon.
[...]
Does anyone have any idea how that could be done, given (as far as I can
see) that you need the horizontal distance to the balloon as well as the
angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.


Known ascent rate of the pilot balloon (AKA pibal) and an azimuth/elevation
angle theodolite reading every 30 seconds plotted on polar graph paper will
produce a vertical wind profile. Trigonometry works, too.
--
TQ

"Brian Salt" wrote in message
k.co.uk...
It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with
finding
the height of the balloon.

The control tower of this airfield was equipped with two pillars to
which
theodolites could be attached/mounted. Apparently, these were used to
determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I
can
see) that you need the horizontal distance to the balloon as well as
the
angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

.... this from "Meteorology for Aviators", HMSO, dated 1939, in the
section dealing with Upper Winds:

" The double theodolite method ... by observing the balloon
simultaneously through two theodolites set up at the ends of a measured
base line, the height of the balloon may be calculated directly from the
various observed angles; for the bearings give a 'fix' to the position
of the balloon. This method requires more time in preparation, and
involves the employment of at least three observers in telephonic
communication. Some improvement is accuracy is obtained for low
altitudes, but in view of the extra time and personnel required, the
method is not suited to the routine observations at an ordinary station
".

I'm curious: *which* airfield in Devon are we talking about? I can't
think of one where the above would be justified - the vast majority of
upper wind finding (in UK) was done on the single theodolite method
using an assumed rate of ascent of a balloon: also, the 22 foot baseline
sounds too short for the above method to be used accurately - though I
could be wrong on that - I suppose if the azimuth readings were taken
very accurately, then a downwind position could be determined OK.

Just a though, was one pillar for a theodolite, and one for a Finemann
Nephoscope - which would also need a pillar? (This latter was also used
for finding upper winds - by chasing features in medium and upper
clouds)

Martin.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with finding
the height of the balloon.

The control tower of this airfield was equipped with two pillars to which
theodolites could be attached/mounted. Apparently, these were used to
determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I can
see) that you need the horizontal distance to the balloon as well as the
angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.


Not sure if you are interested, but we have some balloon weight sets from that
time era. (My company made them at that time)

They are simply a stacked set of plates of various weights so you could change
the weight of the balloon's payload by adding or subtracting plates.

I could e-mail you pictures if you want.

In article ,
(Rileyesi) wrote:

I could e-mail you pictures if you want.

That would be interesting, thank you.
Please remove the 'NS' from the address.

Brian.

Brian Salt.
Remove NS from address before replying.

In article , ToweringQs AT
adelphia.net (TQ) wrote:

Known ascent rate of the pilot balloon (AKA pibal) and an
azimuth/elevation
angle theodolite reading every 30 seconds plotted on polar graph paper
will
produce a vertical wind profile. Trigonometry works, too.

Afraid I don't know the expression 'pibal'!

Please note that I am not a theodolite user. What I am asking is "How
would one do it with just one theodolite?" Perhaps I should look at how a
theodolite works and how it is used :-)

Of course trigonometry works, but you have to have data in order for it to
work.

Brian.

In article ,
(Martin Rowley) wrote:

... this from "Meteorology for Aviators", HMSO, dated 1939, in the
section dealing with Upper Winds:

" The double theodolite method ... by observing the balloon
simultaneously through two theodolites set up at the ends of a measured
base line, the height of the balloon may be calculated directly from
the various observed angles; for the bearings give a 'fix' to the
position of the balloon. snip

That is the method I felt would be used, but, as you say, the baseline of
22 feet is not a useful distance.

I'm curious: *which* airfield in Devon are we talking about? I can't
think of one where the above would be justified - the vast majority of
upper wind finding (in UK) was done on the single theodolite method
using an assumed rate of ascent of a balloon: snip

Harrowbeer Airfield, some 9 miles north of Plymouth.

So what is the single theodolite method?

Just a though, was one pillar for a theodolite, and one for a Finemann
Nephoscope - which would also need a pillar? (This latter was also used
for finding upper winds - by chasing features in medium and upper
clouds)

There is no mention of a Nephoscope is the information we have - and it is
not mentioned on the plans of the watch office/control tower.

Perhaps the need for 2 pillars was to use whichever would be better to
avoid the projection of the balloon filling room, which projects some 8
feet above the roof upon which the pillars are fixed. I can't imagine that
the room for cause any obstruction, but maybe it was 'belt and braces'!

What would a balloon have be used for, given the technology available in
1941-42? Determining cloud base, I suppose, as well as finding the upper
winds?

Brian.

On 2004-11-12 13:38:00 -0500, (Brian Salt) said:


I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with
finding the height of the balloon.

The control tower of this airfield was equipped with two pillars to
which theodolites could be attached/mounted. Apparently, these were
used to determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I
can see) that you need the horizontal distance to the balloon as well
as the angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.

The two pillars probably just meant they had two theodolites.

The method used is based an an assumed rate of ascent. Fill the balloon
with the correct amount of hydrogen or helium, and it would rise at a
calculated rate. Copy down the azimuth and elevation at timed
intervals, then use calculations & now a computer to come up with the
wind direction and speed. I did it all the time as a weather observer.
Just part of the job.




Pete

On Sat, 13 Nov 2004 16:32 +0000 (GMT Standard Time),
(Brian Salt) wrote:

In article , ToweringQs AT
adelphia.net (TQ) wrote:

Known ascent rate of the pilot balloon (AKA pibal) and an
azimuth/elevation
angle theodolite reading every 30 seconds plotted on polar graph paper
will
produce a vertical wind profile. Trigonometry works, too.

Afraid I don't know the expression 'pibal'!

PIBAL (Pi)lot (Bal)loon

Please note that I am not a theodolite user. What I am asking is "How
would one do it with just one theodolite?" Perhaps I should look at how a
theodolite works and how it is used :-)

Of course trigonometry works, but you have to have data in order for it to
work.

Brian.

The US Federal Meterorlogical Handbook #3 is a good reference

http://www.ofcm.gov/fmh3/text/default.htm

Enjoy

Jim

I am setting up to obtain my own data from radiosondes launched
from the Tucson airport. I track the balloon with a small dish (1 meter)
to obtain a good signal and when the sky is clear use a theodolite to
obtain angle as a function of time.
I have only started to track with the theodolite, maybe 4 or 5 times,
and so I don't have the experience of a seasoned observer.

My comment is that it is much harder to do than I thought. Even though
the airport is 5 miles to the south, the angular rates are such that
it is easy to lose track. I tried doing one minute recording to start
off with and have had mixed results. My skill level is getting better
but its still stressful so I am thinking about adding encoders to the
theodolite and logging the data.

My hat is off to WX observers that can track a balloon in high winds.
Maybe if I was at the launch point the rates would be mostly in
elevation making it less demanding.

A baseline of 22 feet sounds like it wouldn't be to useful as the ascent
rates for a standard balloon and fill are known. I would feel better as
an observer just to have a second observer in case I lost track or wrote
down the wrong reading, as I have. I find the mistake when I plot the
data if it's really off, but a second observer would really help.

Dan





Pete Ware wrote:
On 2004-11-12 13:38:00 -0500, (Brian Salt) said:


I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with
finding the height of the balloon.

The control tower of this airfield was equipped with two pillars to
which theodolites could be attached/mounted. Apparently, these were
used to determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I
can see) that you need the horizontal distance to the balloon as well
as the angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.


The two pillars probably just meant they had two theodolites.

The method used is based an an assumed rate of ascent. Fill the balloon
with the correct amount of hydrogen or helium, and it would rise at a
calculated rate. Copy down the azimuth and elevation at timed intervals,
then use calculations & now a computer to come up with the wind
direction and speed. I did it all the time as a weather observer. Just
part of the job.




Pete