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Why do have to read weather like this?



 
 
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  #1  
Old April 22nd 05, 06:37 PM
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Default Why do have to read weather like this?

KHSV 221553Z 19009KT 6SM BR FEW020 BKN035 OVC100 19/18 A2986 RMK
AO2 TSE00RAE11 SLP104 TS MOV NE P0000 T01890178=

I know, and I can read it. And someone is going to say that they
prefer it that way.

I can just see an ASR-33 Teletype machine jumping up and down and
saying that 10 characters per second is what God made for us.

Kind of like the farmers here who said that we were messing with God's
time when we went to daylight savings time.

Rant still on,

Mike Weller


  #5  
Old April 24th 05, 05:26 AM
Brian Burger
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On Fri, 22 Apr 2005, Nathan Young wrote:

On Fri, 22 Apr 2005 12:37:54 -0500, wrote:

KHSV 221553Z 19009KT 6SM BR FEW020 BKN035 OVC100 19/18 A2986 RMK
AO2 TSE00RAE11 SLP104 TS MOV NE P0000 T01890178=

I know, and I can read it. And someone is going to say that they
prefer it that way.


I prefer it this way. Once you are used to it, it is shorthand, and
is quicker to read than the longhand version, which would read
something like this...


Not only that, the basic format is international. Everything before RMK is
pretty standard worldwide, so I (a Canadian) don't have to know exact
details of how the US does their weather reports. I can just run through
the standard code.

The US NOAA/FAA ADDS wx website allows you to check *any* airport or wx
reporting site w/ a standard code. The reports aren't all "translated"
into the US standard encoding system, but the fundamentals should be
readable by anyone with a private pilots license.

Besides, I really can read the coded versions far faster than the "plain
language" versions, and that's true of many, many pilots. Get a half-dozen
airports onto one screen (or sheet of paper) and compare them all at a
glance, more or less.



Huntsville International Airport, April 22, 1553Z weather. Winds
190@09kts, 6 statute miles visibility in mist. Few clouds at 2000
feet, broken cloulds at 3500 feet, overcast clouds at 10,000 feet.
Temperature 19 deg C, dewpoint 18 deg C, Altimeter 29.86...


Or even longer versions. Check how NavCanada does "plain language" wx
reports for seriously verbose
translations.(
www.flightplanning.navcanada.ca) The code versions are three
lines; the "plain" ones are half a screenful...

The encoded METAR/TAFs might have started as a reaction to low-bandwidth
telegraph/teletype machines, but they're still a remarkably effecient way
of delivering wx data to trained people!

Brian
PP-ASEL/Night
  #6  
Old April 22nd 05, 07:22 PM
Michael 182
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We don't. There are at least a dozen translator tools out there, including
DUATS and ADDS.

Michael

wrote in message
news:1114190529.b66f5cddb1aec1ba47dfaf0f4432d36e@o nlynews...
KHSV 221553Z 19009KT 6SM BR FEW020 BKN035 OVC100 19/18 A2986 RMK
AO2 TSE00RAE11 SLP104 TS MOV NE P0000 T01890178=

I know, and I can read it. And someone is going to say that they
prefer it that way.

I can just see an ASR-33 Teletype machine jumping up and down and
saying that 10 characters per second is what God made for us.

Kind of like the farmers here who said that we were messing with God's
time when we went to daylight savings time.

Rant still on,

Mike Weller




  #9  
Old April 22nd 05, 09:56 PM
Peter Clark
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On Fri, 22 Apr 2005 19:55:22 GMT, Nathan Young
wrote:

It is not as trivial as it should be. METAR decoder software is
difficult to write because of the special weather statements that can
be included in a METAR entry (things like RVR, multiple precip types,
etc).

Simple parsers can grab winds, date, time, and cloud conditions. But
to be all-encompassing requires a bit more. I found a package (via
NOAA?) that would do METAR decodes, and it included approximately 30KB
of source code, which seemed like a lot for the extra bit of
functionality it provided.


30K just for the parser, or did that include station name lookup
tables? Seems like the code should just do one pass through a
relatively straightforward nest of if/thens/elseif. Load the METAR
into an array since each element is space-delineated, the first two
elements are going to be the station name and time of issue (assuming
no SPECI). Then the rest of the code would be if/then for the
multiple elements. So, 19015G32KT 1SM -RA BR BKN010 BKN035 OVC050
would be IF (windtype) THEN (printwind) ELSIF (visibility) THEN
(printvis) ELSEIF (preciptype) THEN (printprecip) ELSIF (cloudtype)
THEN (printcloudtype) ELSIF (temp) THEN (printtemp) (blah blah blah) -
rinse/recycle/repeat the analysis for all non-null elements in the
array..

I think the problem with most of the decoders I've seen is that they
expect METAR elements in fixed positions and only code for the base
case and don't do any processing. Old weather injectors for MS Flight
Sim are good examples of this. Get an RVR in there and they'd have
cloud base numbers for the temp and all sorts of nasty errors.
  #10  
Old April 22nd 05, 10:10 PM
Icebound
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"Peter Clark" wrote in message
...
On Fri, 22 Apr 2005 19:55:22 GMT, Nathan Young
wrote:

It is not as trivial as it should be. METAR decoder software is
difficult to write because of the special weather statements that can
be included in a METAR entry (things like RVR, multiple precip types,
etc).

Simple parsers can grab winds, date, time, and cloud conditions. But
to be all-encompassing requires a bit more. I found a package (via
NOAA?) that would do METAR decodes, and it included approximately 30KB
of source code, which seemed like a lot for the extra bit of
functionality it provided.


30K just for the parser, or did that include station name lookup
tables?



Like most computer code, 20 percent of it probably does the real work....
and the 80 percent is there to make sure that it exits elegantly and does
not run into an infinite loop, crash-to-operating-system, or report
ridiculous value... whenever it is fed garbage input or exceptional
conditions.




 




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