Heat Index

[jjocsak]

Can this be included in the graphs somewhere just like the wind chill?

Jeff

[steve]

In version 2, yes.

I'll try to find time to do it in version 1, but there are a few issues with that; it's not currently logged, and the way the graphing works requires that. It would have to go on the outside temperature graph, and four lines might make it a bit too busy. I'd probably want to make it an option, as I suspect not everyone would want it - I wouldn't, for example, as the temperature here is never high enough to make heat index any different from ambient temperature. But as long as it came before the temperature, it would just disappear under the temperature line anyway, like wind chill, so I guess that's not really a problem.

[steve]

Give this a try, please: http://nybbles.co.uk/downloads/beta188/CumulusSetup.exe

[jjocsak]

I see the reference to heat index in the select-a-graph and graphs but don't see any data associated with them.

Jeff

[steve]

You won't see any data from the point before you ran the new version; it wasn't logging the heat index previously, so has nothing to plot.

[jjocsak]

OK thanks.

Jeff

[jjocsak]

Steve, the heat index is working great.



Thanks
Jeff

[Super-T]

I don't seem to get the heat index showing on the graph but it is in the heading. Tried changing the colour but no joy. I see that Wind Chill and Heat Index are similar readings so Heat Index should be somewhere near the Wind Chill line.
Select a Graph shows data OK.
Any ideas anyone?

[beteljuice]

You haven't got warm enough for HI to be applied - so it's probably 'tied' to current temperature.

BTW you can't have windchill and HI at the same time

[steve]

BTW you can't have windchill and HI at the same time

Just as well Cumulus doesn't show them both on the graph at the same time, then

I'm still undecided as to what to do in Cumulus 2. Yes, you're absolutely right that there is no wind chill effect under certain conditions, and no heat index effect under certain (different) conditions, but my view is that it's valid to show the current temperature for these items when the effect doesn't apply. It's confusing to show null/dashes/NA/whatever. My support load would certainly increase if I did that

At the moment my thinking is that Cumulus 2 will do the same as Cumulus 1, but I will probably add the combined 'feels like' index. And maybe an option to show null/dashes/NA/whatever for the other two when they don't apply.

[beteljuice]

At the moment my thinking is that Cumulus 2 will do the same as Cumulus 1, but I will probably add the combined 'feels like' index. And maybe an option to show null/dashes/NA/whatever for the other two when they don't apply.

Wasn't making a Cumulus comment Steve, just stating the not obvious for others.

I agree with the common, but incorrect, PWS philosophy that ties N/A to current values (a hangover from from early limited telemetry / processing I suspect).

However; it is these 'always there' values that makes people think they must be being applied

I initially didn't really appreciate the "Feels Like" value, but once I realised I could have two temperature entries that made immediate sense rather than three and scratch my head - it got my vote

[jjocsak]

You haven't got warm enough for HI to be applied - so it's probably 'tied' to current temperature.

BTW you can't have windchill and HI at the same time

This is close.



I wonder if there is something wrong?

Jeff

[Super-T]

I should have looked up the definition of Heat Index before asking silly questions
We have a few months to go yet before the Heat Index will show up as separated from the temp.....unusual to go over 28C in Auckland.

[steve]

I wonder if there is something wrong?

Yes, in fact I noticed this anomaly yesterday while implementing the wind chill algorithm in Cumulus 2 and comparing it with the current version. Strictly speaking, Cumulus should not apply a wind chill effect unless the temperature is less than 10 C. By default, it doesn't apply this rule; to get it to apply the rule you have to edit cumulus.ini and add a line to the [Station] section:

UseWindChillCutOff=1

I can't remember why I did it this way. Presumably I forgot to put the check in initially, and then when it was pointed out to me, I added it as an (undocumented) option. I think I may change the default in the next build.

[jjocsak]

Thanks Steve, I'll keep an eye on it.

Jeff