Diurnal temperature variation

[wd40]

Best I can tell this is the same as Cumulus's Lowest or Highest Daily Temp Range. Is that right?

I was doing a bit of digging on the use of the Lowest or Highest Daily Temp Range. Anybody know of a good web page on this range.

[b.e.wilson]

I don't know a particularly outstanding page, only this:
(min) the daily minimum, absent any fronts blowing through, happens sometime after 3 am on a cloudy or humid night, when the ground temperature equilibrates with the air temperature, or just before sunrise on a dry and cloudless night, when the outward radiation of heat is stopped by the warming of the sun.
(max) the daily maximum happens after the noon hour, as late as an hour before sunset, depending on the cloud conditions (I know, it's vague, but daily highs are more dependent on atmospheric effects than the lows).

So if you want the dinural range, whether you start the day at midnight or at 9 am changes which calendar day the night time low is attributed to. Now, I realize this was your question: in tallying up the dinural day, does the nighttime low come first, then the daily high, or does the high happen first, then the daily low?

I count the low first, then the high (the "day ends at midnight" mode) so that the low and the high happen on the same calendar day. Beyond that I do not know the standards.

[wd40]

Bruce thanks for the reply.

The question comes from the record lowest and highest temp range that is happening since Steve installed it in one of the latter builds.

Since the information is there I wanted to find out how it might benefit. I did run across a place that said these numbers are very important for vineyards since the range can directly effect the sugar and acid content of the grapes.

I do make my own wine from our US native grape in the South called Muscadines.

Randy