From: Tom Pollard <tomp@...>
Date: 2007-01-27T16:07:44+09:00
Subject: Re: Ruby WX (weather)


On Jan 27, 2007, at 1:30 AM, Hans Fugal wrote:
> There's plenty left to do if you're interested. Remark parsing is one
> big task that I haven't even begun to tackle yet. The other major TODO
> items:
>
> - a fetch method to grab the METAR from the web and parse it

That's really a separate concern from parsing the METAR, and quite  
simple to do.  I just included a couple of sample scripts with my  
package that demonstrated how to grab a current observation from the  
web and produce a report.

> - human-readable output

For the following METAR string...

METAR KEWR 111851Z VRB03G19KT 2SM R04R/3000VP6000FT TSRA BR FEW015  
BKN040CB BKN065 OVC200 22/22 A2987 RMK AO2 PK WND 29028/1817 WSHFT  
1812 TSB05RAB22 SLP114 FRQ LTGICCCCG TS OHD AND NW-N-E MOV NE P0013  
T02270215

.. the 'to_string' method on the resulting 'Metar' object returns:

station: KEWR
type: routine report, cycle 19 (automatic report)
time: Thu Jan 11 18:51:00 2007
temperature: 22.7 C
dew point: 21.5 C
wind: variable at 3 knots, gusting to 19 knots
peak wind: WNW at 28 knots
visibility: 2 miles
visual range: on runway 04R, from 3000 to greater than 6000 meters
pressure: 1011.5 mb
weather: thunderstorm with rain; mist
sky: a few clouds at 1500 feet
      broken cumulonimbus at 4000 feet
      broken clouds at 6500 feet
      overcast at 20000 feet
sea-level pressure: 1011.4 mb
1-hour precipitation: 0.13in
remarks:
- Automated station (type 2)
- peak wind 28kt from 290 degrees at 18:17
- wind shift at 18:12
- frequent lightning (intracloud,cloud-to-cloud,cloud-to-ground)
- thunderstorm overhead and NW-N-E moving NE
- TSB05RAB22

One bit of unfinished business was to provide a class to represent  
reporting stations, so that the above observation could be reported  
as being for "Newark Airport, Newark, New Jersey" - rather than  
'KEWR'.  Also, I thought it would be useful to allow it answer  
questions like, "what other reporting stations are with 50 miles of  
KEWR?", etc.

> - internationalization, e.g. different units (this one's not so big)

It looked like your parser already handles different units on input.   
Do you mean adding support for reporting the observations in  
different units?  I had hoped the ruby units module would make that  
simple.  I ended up more-or-less writing my own units module for the  
Python parser.

Tom