Re: [mh] Apparent Temperature is too high

[Matthew W. <mat...@us...>]

Tom wrote:
> I just noticed that the apparent temp and the actual temp are identical 
> and they have been since the change was made.
> According to http://weather.noaa.gov/weather/current/KPDK.html, which is 
> the station information I'm using, the Temp is 96.1 and the Heat Index 
> is 95.2.
> Is there anything you'd like me to try?
> 
> tom

The formula that I implemented is only valid for humidity levels >= 40% and
temperatures >= 80, otherwise we set HeatIndex = TempOutdoor.  Looking at
the NOAA site, it looks like your humidity is only 33% (at 8:57p EDT), so
the Heat Index formula doesn't apply.

As I mentioned before, the Heat Index is a best-fit formula to an empirical
curve.  The formula in Weather_Common is a quadratic in two variables (not
sure if that's the right term).  It contains all possible terms where Temp
and Humidity are involved up to a power of 2 with 9 total terms.  There was
also a matrix formula presented that includes all terms up to a power of 3
for a total of 16 terms.  There was no direct reference for the 2nd formula
as to which ranges of humidity and temperature is was accurate for, so I
opted for the formula whose conditions were known.

Now, I would be happy to update the formula to the 16 term version if we can
find a source that also gives the ranges where it is valid.

Matt
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