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Re: [Phys-L] depicting uncertainty on maps



What I believe is now going on with the cable news and major network weather predictions is a tendency to come up with "storm of the century" type predictions which will "seriously impact tens of millions" of viewers. These predictions are usually (although not always, of course) over blown. I correlate this hyperbolic behavior with a desire to increase the number of viewers (which would then, as you point out, also correlate with increased ad revenue from sponsors). Unfortunately, such behavior also correlates with growing public distrust of the media.
Don
-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@mail.phys-l.org] On Behalf Of Bill
Norwood via Phys-l
Sent: Wednesday, March 15, 2017 9:47 AM
To: Phys-L@phys-l.org
Cc: Bill Norwood <bnorwood111@gmail.com>
Subject: Re: [Phys-L] depicting uncertainty on maps

Don,
- I think that it would be more productive to try to correlate weather
predictions with marketing needs.
- For example, if winter wear sales has taken a hit, expect more dire
forecasts involving low temperatures, snow, ice, wind etc.
Bill Norwood, U of MD at College Park

On Tue, Mar 14, 2017 at 12:18 PM, Donald Polvani <dgpolvani@verizon.net>
wrote:

In my local area (near Baltimore, MD) the local weather station is now
putting out "contour area maps" with a range of snow falls specified
within each area (e.g. 1 - 3 in, 3 - 5 in, etc.). This same procedure
could have been used with the experimental NWS page, since the
specified overall area stayed the same with only the internal contour
lines changing from map to map. As a user of the information, it's
simpler for me to just have to look at one map rather than three, and
I should get the same predicted snowfall range for my particular
location. Averaging the low and high values to get the expected value
is pretty simple to do in one's head. Of course putting all the
information on one map also saves the weather person and the TV station
expensive presentation time.

Don
-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@mail.phys-l.org] On Behalf Of
John Denker via Phys-l
Sent: Tuesday, March 14, 2017 9:33 AM
To: Forum for Physics Educators <Phys-L@Phys-L.org>
Cc: John Denker <jsd@av8n.com>
Subject: [Phys-L] depicting uncertainty on maps

Hi --

Here is a timely example of uncertainty handled in an intelligent way.
Note the contrast:
++ For a point forecast, the National Weather Service routinely
expresses
the uncertainty in the amount of snowfall by quoting a range, e.g. 12
to 18 inches. In physics it might be more conventional to write that
as 15±3 inches, but quoting the range is perfectly reasonable also.
-- On a map, the contours and color-coding don't lend themselves to
representing a range.
++ You can do a lot better by putting out *three* maps: lower limit,
nominal, and upper limit. The NWS has an experimental page that
does just that. Here is a screen grab:
https://www.av8n.com/physics/img48/snowfall-map-brackets.png



By way of contrast, note that as usual in the real world, the
uncertainty is
neither calculated nor communicated using sig figs or anything like that.
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