[kwlug-disc] cli weather

[Chris Frey]

On Mon, Feb 19, 2024 at 10:27:54PM -0500, Steve Izma wrote:
> One odd thing about the symbols used in the downloaded data, I
> think: the arrows that indicate wind direction seem ambiguous.
> When a weather report says something like "winds westerly", it
> means that the winds come from the west, but the arrows
> point at the direction from which the wind comes, making the
> motion seem 180 degrees off. Is this standard in weather
> symbolism, or is the author of the resource misinterpreting the
> idea?

Wind is normally reported where it's coming from:

	https://en.wikipedia.org/wiki/Wind_direction

It's common in aviation:

	https://aviation.stackexchange.com/questions/26549/how-is-wind-direction-reported-blowing-from-or-blowing-to

Wind 270 at 10 means wind coming from the West, to the East, at 10 knots.

A weather vane on a farm would normally point into the wind as well,
with an arrow.  On the other hand, a windsock floats in the direction
the wind is travelling.

It does get confusing on the web though.  If I look at:

	https://www.windfinder.com/forecast/toronto_island

In the top right corner, the current wind report says "Southwest" at
6mph, with an arrow pointing northeast. :-)   I'm not sure what's going on
there, although it suggests that arrows on "user-friendly" weather
reports are showing wind direction, not source.

Compare that to wind barbs and fun "winds aloft" charts:

	https://windy.app/blog/learn-to-read-wind-barbs.html

The barb can be looked at like an arrow, with the feathers end at
side the wind is coming from, and the dot on the side the wind is going.

But let's do some comparisons.  As of right now:

	https://weather.gc.ca/city/pages/on-82_metric_e.html
	Says wind is: SSE 4 km/h

	https://www.worldweatheronline.com/kitchener-weather/ontario/ca.aspx
	Says wind is: SE 6 km/h

	http://wttr.in/kitchener
	Says wind is: 6 km/h, with arrow pointing up and to the left (NW)

	https://flightplanning.navcanada.ca/cgi-bin/Fore-obs/metar.cgi?format=raw&Langue=anglais&Region=can&Stations=CYKF,CYXU,CYHM
	METAR data from Kitchener airport (CYKF) says:
	METAR CYKF 200500Z AUTO 15002KT 9SM BKN200 BKN220 M09/M10 A3027 RMK SLP272=
	Which when parsed, says as of midnight (about 20min ago)
	wind is coming from 150 degrees (SE) at 2 knots.

So I'm starting to think there is a bug in wttr.in, or it is following
windfinder's style and showing the direction.

- Chris