Webtags (preserving history): Difference between revisions

The new links to material that has been moved off this page can be found approximately where the material used to be within two sections on this page: [#Input Modification Parameters and Output Modification Parameters]] and  [[#The tag name]].

 

If you have not used this Wiki page before, or are unsure about using "web tags", there are some concepts that you do need to understand in the sub-sections that follow.

[[File:Crystal Clear info.png|40px]]

 

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Weather values are always changing, so Cumulus needs a way for you to tell Cumuluss to enter the current value for a particular derivative, when it is [[Customised_templates#What_is_meant_by_.27Cumulus_processes_templates.27|processing templates]].

''This sub-section applies to releases up to 3.11.4.'' (From 3.12.0, use the admin interface and Station settings → Common Options → Advanced options, to get to where you change this setting, instead of editing the file as described below).

In [[#Scary_statistics]] section of this page, it is explained how less than a thousand [[#Full List of Tag Names|tag names]] as they are only part of the [[#General Format for Web Tags]] become billions of web tags, simply by adding modifiers.

The modifiers available used to be listed on this page (so if you select the history tab for this page, you will find references to their introduction and growth).  There are some advantages in moving them to the new [[Webtags/Parameters|web tag parameters]] page:

* This page is very long, even without the parameters

* Having them on separate pages means you can have two tabs (or two separate browsers) open so you can see both the tag name and the modifier parameter by flicking between tabs,instead of lots of scrolling.

* A score of [[Webtags/Parameters#Input_modification_Parameters|input modification parameters

* All about the complex subject of modifying the way a '''duration''', a ''date'', or a  '''clock time''' is output by looking [[Webtags/Parameters#Multiple_Output_Format_Modifier_parameters_for_times_and_dates|here]]

MX uses a '''token parser''' to read the web tags and replace them with the correct value, so if diagnostic output refers to tokens, it is saying the attempt to actually work out what content to return to replace the web tag with its tag name and parameters has encountered a problem.

|The average rate of change in temperature over the last three hours. Trend = (temp_now - temp_3hrs_ago) / 3

|Temperature change over the last three hours - Rising/Falling/Steady (for use by [[Webtags_as_boolean_operators_in_HTML|HTML]], [[Editing_content_of_a_webpage_using_either_HTML_or_Script|javascript]] etc, values can't be changed)

|The average rate of pressure change over the last three hours.

| a singe word description for the pressure trend - Rising/Falling/Steady (for use by [[Webtags_as_boolean_operators_in_HTML|HTML]], [[Editing_content_of_a_webpage_using_either_HTML_or_Script|javascript]] etc, values can't be changed)

| Air Quality expressed in terms of particulate matter of 2.5 micrometres or less

| Air Quality expressed in terms of particulate matter of 2.5 μm, or less, Last 24 hours average

 

| Air Quality expressed in terms of particulate matter of 10 μm, or less

| Air Quality expressed in terms of particulate matter of 10 μm, or less, Last 24 hours average  

 

| Temperature as reported by Air Quality monitor

| Air quality 1

|Leak sensor - 0 or 1  

There are a set of web tags for 'recent historical data', based on an array stored by Cumulus giving data values from 1 minute ago, up to 1 week ago, in 1 minute intervals. As Cumulus runs it will add the latest values to the array with full resolution, and shift existing values along so those older than 7 days fall off. 

*The input modification parameters available are listed at [[Webtags/Parameters#Input Modification Parameters for Recent History]].

**To save you looking up the details, these input parameters specify how many minutes ago is required. Instead of entering a very large number for minutes, you can include separate input parameters for days, hours, and minutes, ago.

**Examples appear in the table below, with explanations

Following the table giving the tag names actually available, there is a section on how to derive a few more weather derivatives using a combination of the tag names shown.

 

 

 

 

=== Table of Recent History web tags available ===

 

[[#No_Commas]] versions of the array are available for use in script. If you use MX, the tag names in this table can take a [[Webtags/Parameters#Output Modification Parameter for Removing Commas|rc=y]] parameter.

|Wind Chill (if temperature is below 10°C or 50 °F, then the new Feels Like now available in MX (next item) will report this same value).

|colspan="3" style="background:lightgray;"|Wind

|Wind Latest. Note: Wind 'Speed', 'Gust' and 'Latest' have the usual Cumulus meanings

=== Other weather derivatives ===

Although Humidex, 'Apparent Temperature', 'Feels Like temperature' and others listed in Current Conditions section, are not available at all versions, they can be calculated in a script from recent 'outside temperature', 'wind speed', and 'relative humidity' values (using the same time selection for all). There are other derivatives that can be calculated similarly from a set of simultaneous values. Note that Cumulus 1 and MX do not always use identical formula, and although MX added Feels Like it has changed the formula a few times.

 

The relevant formulae using JavaScript, adjust for other languages, for some of these are shown below:

 

==== Canadian Humidity Index ====

 

 

Cumulus 1:

 

H = <#RecentOutsideTemp h=3> + 5/9 * (6.1094 * Math.exp(5417.753 *(1/273.16 - 1/ (273.16 + <#RecentDewPoint h=3> )))-10);

 

Cumulus MX:

 

svp = 6.112 * Math.exp((17.62 * <#RecentOutsideTemp h=3) / (243.12 + parseFloat(<#RecentOutsideTemp h=3)));

H = (5/9 * (<#RecentHumidity h=3> /100 * svp - 10)) + <#RecentOutsideTemp h=3;

 

==== Apparent Temperature and Feels Like ====

 

Note this apparent temperature formula uses Celsius for temperature and '''metres per second''' for wind speed. You will need to do the appropriate conversions from the quoted recent history tags if you use different units.  The Australian Apparent temperature formula is same for Cumulus 1 and MX:

 

var actualVaporPress = <#RecentHumidity h=3>/100) * 6.105 * Math.exp(17.27 * <#RecentOutsideTemp h=3>) / (237.7 + parseFloat(<#RecentOutsideTemp h=3>))));

var appTempDegC = parseFloat(<#RecentOutsideTemp h=3) + (0.33 * actualVaporPress) - (0.7 * <#RecentWindSpeed h=3>) - 4;

 

Feels Like was implemented as a recent history web tag at version 3.6.11 (see [[#Feels_Like|Feels Like section below Current condition web tags]]) for the gradual introduction of feels like elsewhere. For earlier MX versions, and if you are using Cumulus 1, you can calculate it:

 

The formulas below use Celsius for temperature and '''km per hour''' for wind speed. Again, you will need to do the appropriate conversions from the quoted recent history tags if you use different units.

 

Calculation from recent history tags is much more complicated because there are 3 different calculations: Feels Like reports exactly same as wind chill for temperatures '''below''' 10°C or 50°F so the WC here should equal <#RecentWindChill h=3>:

<pre>if(<#RecentWindSpeed h=3> < 4.828) WC = <#RecentOutsideTemp h=3>;

wind_pow =  Math.pow(<#RecentWindSpeed h=3>, 0.16);

WC = (13.12 + 0.1625 * <#RecentOutsideTemp h=3>) - (11.37 * wind_pow) + (0.3965 * <#RecentOutsideTemp h=3> * wind_pow);// Brackets used to ensure "+" is interpreted as addition not concatenation

 

For temperatures '''above''' 20°C or 68°F Feels Like uses a different way to calculate apparent temperature that it uses at these higher temperatures (this formula only used for 3.6.10 onwards):

<pre>var actualVaporPress = <#RecentHumidity h=3>/100) * 6.112* Math.exp((17.62 * <#RecentOutsideTemp h=3>)/(243.12 + <#RecentOutsideTemp h=3>)) / 10.0;  // Not same as at build 3084

if(<#RecentWindSpeed h=3> > 72) <#RecentWindSpeed h=3> =72;

AT= (1.04 * <#RecentOutsideTemp h=3>) + (2 * actualVaporPress) - (0.1805553 * <#RecentWindSpeed h=3>) - 2.7;</pre>

 

For in-between temperatures it uses a more complicated merge of the two formulas for AT and WC as defined above:

<pre>app_temp_mult = (<#RecentOutsideTemp h=3> - 10) / 10;

 

|-

!style="width:150px" | Web tag_name

!style="width:650px" | Function

|-

|<#snowdepth>

|Meteorologists report snow depth in cm, so this is default unit for Cumulus.  

 

If there is no entry in Weather Diary for the day explained above, reports zero.

 

[[File:Badge vMx.png]] Input is to 2 decimal places. Available from version 3.1.1 - build 3054 when weather diary editor was added to MX.  MX allows output in centimetres with decimal places without any script. You can't change the units shown in admin interface, but your value can be input as inches to 2 decimal places if you ignore "cm" that is displayed in that interface.

 

[[File:Badge v1.png|Fil]] Input and output is always as integer. Available from very early builds, weather diary input amended from version 1.8.6 14th April 2009 to allow units to be specified on diary edit screen. If you choose to enter as whole millimetres,  you can use JavaScript (or another script language) on your web page to divide the web tag by 10 and get centimetres to 1 decimal place on output.  

|-

|<#snowlying>

| [[File:Badge vMx.png]] Available from version 3.1.1 - build 3054.  If there is no entry in Weather Diary for the day explained above, , this web tag returns Null. Otherwise reports 1 if tick in diary, 0 is unticked.

 

[[File:Badge v1.png]] Although this tag is not available in Cumulus 1, your web page can use a script to check if <#snowdepth> is non zero, as that means snow is lying

|-

|<#snowfalling>

| [[File:Badge vMx.png]] Available from version 3.1.1 - build 3054.    If there is no entry in Weather Diary for the day explained above, , this web tag returns Null. Otherwise reports 1 if tick in diary, 0 is unticked.

 

[[File:Badge v1.png]] Not available in Cumulus 1. There is no web page workaround, unless you write a script that reads [[Weather Diary]] and makes relevant information available on your web server.

|}

 

===Today.ini===

 

As explained earlier, these tags relate to latest [[Meteorological day]], except for Sunshine Hours which relate to latest Calendar day.

 

Information for these tags is taken from [[today.ini]], hence the sub-section title, although Sunshine Hours can be taken from either [[yesterday.ini]] or "today.ini" depending on (respectively) whether before or after rollover time if that is not midnight.

 

 

For web tags that report values that refer to a particular time of day, there is a corresponding web tag that can give the time of day, shown in same row of table below. For those that cover whole day so far, the final column contains "n/a".

 

Please note none of the time web tags can be modified by output parameters to give a date, but they can be changed from the default time format that is 'H:mm' (24 hour clock notation without leading zero for hour) for Cumulus 1 and MX.  

 

If you are using output modifiers to change how the time is reported, be careful to use ones that work for the flavour of Cumulus you are using ('H' and 'h' are same for Cumulus 1, but the two codes represent different formats for MX; MX insists on 'mm' being used for minutes, but the 'NN' and 'nn' used by Cumulus 1 could be replaced by 'mm' if they followed an hour specifier).

| <#windAvgY>>

|<#SunshineHoursY>

This year's highest Daily Wind Run

These are a set of tags for monthly all-time highs and lows, in other words the highest and lowest values for a particular month of the year.  To supply both optional input modification, and optional output modification parameters, separate them with spaces, e.g. <#ByMonthTempHT mon=7 format=hh:nn>. In that example, the highest ever temperature in July is returned in the value after processing by Cumulus.

 

For full details of the input modification parameters, see [[Webtags/Parameters#Input_modification_Parameters|Parameters]] page.

Additional tags correctly populated from 3.6.10 (build 3086) or 3.7.0 (build 3089) are marked with a "MX" icon as they are not available in Cumulus 1. Please note the 3.6.10 release was available from 24 June 2020, if the date/time shown for those MX only tags is before when you installed that (or a later release), the feels like output may show incorrect values.