Cumulus Support

I don't get why you wish to use the max/min method when the average temp is already present in the dayfile (CMX averaging)

The only thing you need to do is summing it up.

And btw, I already implemented both charts in Cutils (including a parametrised base temp).

HansR wrote: ↑Mon 19 Apr 2021 10:14 am I don't get why you wish to use the max/min method when the average temp is already present in the dayfile (CMX averaging)

Because the average in the dayfile does not take the 30C upper limit into account.

Likewise, the maximum temperature is usually capped at 30 °C because most plants and insects do not grow any faster above that temperature. However, some warm temperate and tropical plants do have significant requirements for days above 30 °C to mature fruit or seeds.

usually...: a lot of effort for a non-generic requirement which....
Anyway, all clear now.

Here is a rough implementation of GDD in the standard template: https://weather.wilmslowastro.com/test/ ... storic.htm

As you can see, the number of data series becomes problematic. I'm not sure how to handle that, other than create another sort of select-a-graph solution that allows you to compare a few years at once.

Hi Mark,
The graphs look very nice. They can get congested when looking at say all GDD1 from 2010 to 2021, but the drop down table provides the details

Enjoy,
Paul

I'm struggling to understand the usefulness of the heat accumulation?

The graphs @pes has linked, show the accumulation going below zero, I would have thought you would have a threshold, and add the accumulation above that threshold.

My logic is that once the temperature drops below the point at which something stops happening (trees growing for instance), it stops, it can't stop more the lower the temperature?

I think I must be missing something

mcrossley wrote: ↑Wed 21 Apr 2021 12:30 pm I'm struggling to understand the usefulness of the heat accumulation?

The graphs @pes has linked, show the accumulation going below zero, I would have thought you would have a threshold, and add the accumulation above that threshold.

My logic is that once the temperature drops below the point at which something stops happening (trees growing for instance), it stops, it can't stop more the lower the temperature?

I think I must be missing something

It does not matter, it is just how you shape the graph.
You let the line begin as soon as it goes above zero so over the years the above zero point shifts just left and right for the start of the growing season.
Same for topping off at the end of the year (horizontal end of the line)

I implemented it just straight forward. The advantage of not using a threshold is that you get an impression of the strength of winter or (at the end of the line) an early/late start of winter. It is simply a display of a function, don't make it too complex or give it too much meaning. Just draw the line. The user interprets (that's what happens with heuristics). This year e.g. we had now several warm days in rather cold periods so you see the line below zero suddenly rise and than flatten again. The user then can search his data what was happening there. If you just cut that off, the development of the weather in winter gets lost.

You are not missing anything except maybe some agricultural pragmatism
Too much beta ?

OK, fair enough.

The only way I can get any year of my data to go negative is by starting the year in December, then 2010/11 goes down to -51
Did you know the UK is mild and wet!

There are two graphs: Temp Sum and GDD

this is my code for the GDD: And this is for the Temp Sum (only temps > 0 are counted): Don't ask why, that's how it is done (in NL), no doubt there are variations.
And you always start on January first.
That's what happens with heuristics: sloppy theory gives sloppy graphs

Isn't that the wrong way around. The GDD should use the threshold, and the Sum not!

GDD is: (avg > threshold) ? avg - threshold : 0

GDD never goes negative.


Anyway, a snapshot of my data on my test default web site (new Temp Sum button)...

https://weather.wilmslowastro.com/test/ ... storic.htm

mcrossley wrote: ↑Wed 21 Apr 2021 1:35 pm Did you know the UK is mild and wet!

How about NL?

That is why the seasonal graph actually is more important in the Nordic countries (or Canada, Siberia etc...). The Temp Sum is more relevant in the milder zones (e.g. in NL it is used for tulip bulb calculations in the Keukenhof). They can't predict the start of the bloom, but they can predict the relative time distances so to have continuous flowering. That is the magic for which all tourists (yes Brits as well) come and watch: how do they do it.... well, simple arithmetic and measurement.

And apart from that: season (GDD) is very vegetation dependent. In countries where there is no frost (or hardly frost) there definitely is season. You just have to define your limits. In NL the winter temp would not be defined at 0 but probably at 4 degrees. Agriculture is fluid, that is why these graphs are interesting but they are not really meteorological charts.

For these charts configuring, explanation and understanding is not irrelevant.

mcrossley wrote: ↑Wed 21 Apr 2021 1:50 pm Isn't that the wrong way around. The GDD should use the threshold, and the Sum not!

GDD is: (avg > threshold) ? avg - threshold : 0

GDD never goes negative.


Anyway, a snapshot of my data on my test default web site (new Temp Sum button)...

https://weather.wilmslowastro.com/test/ ... storic.htm

Not like @Pes does, not like I do it.
Two different implementations. Interesting.

I cannot find a single reference or online calculator that uses negative GDD values. Can you please provide one.

I can accept using all values for the sum of averages - it shows the depth of winter which may be useful.

But do plants have negative growth - I can see they stop, eventually get damaged, or killed by really low temps.

I find this data and discussion interesting. I didn't inherit my father's farming knowledge, and left the fields to pursue other happiness... but each spring I look forward to gardening and keeping things green and growing. I also watch when area farmers want or can get on to their fields for preparation of planting season. But our seasons have quite a range of weather. Over the past couple of weeks I have nurtured my little yard and flower beds when we were teased early with spring-like conditions. But this morning woke and found the ground covered with 5.5 cm of snow.

In trying to follow this discussion I looked at my Annual Data, thanks beteljuice for that excellent script, and for a few of the years listed the number of days each month with average temperature of >5°c. That pretty well sums up that our start of spring can vary quite a bit - i.e. for the period 2009-2021 March has about 10 days with average temp above 5°; over that period an average daily temperature of 1.3° with a one day average of 7.9° in 2012 for the highest, and -3.4° in 2014 for the lowest.

I am in the southern-most part of the country in prime agricultural mixed farming area. In a search of EC GDD I found an interesting interactive site https://www.agr.gc.ca/atlas/agclimate
By using the Map selector It looks like data is recorded each Monday during the April-October period, and the occasional additional day for precipitation and temperature (GDD). It is interesting looking at the details, i.e. Monday April 12, 2021 is the latest recorded, and how the GDD differ.

I think having that GDD in Cumulus will be is interesting, and gives me a head start in debating weather with neighbours

Enjoy,
Paul

@Paul: thanks Paul, a site to remember.