Webtags (preserving history): Difference between revisions

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|<#feelslike>
|<#feelslike>
|The current [[Feels_Like|Feels Like]] temperature.  The referenced page in weather terminology section of this Wiki explains it. Although output from version 3.5.4 build 3075, the correct value is only available from version 3.6.10 (build 3086) onwards as incorrect formula used in builds 3084 and 3085, and a different formula used in builds from 3075 to 3083.
|Not available in Cumulus 1. Not available in all MX versions. Please see sub-section below this table regarding availability by MX versions if you are using a MX version earlier than 3.6.10.
 
The current [[Feels_Like|Feels Like]] temperature.  The referenced page in weather terminology section of this Wiki explains it.
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|<#IsFreezing>
|<#IsFreezing>
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|<#RecentWindChill>
|<#RecentWindChill>
|Wind Chill
|Wind Chill (if temperature is below 10°C or 50 °F, then the new Feels Like now available in MX will report this same value).
| <#RecentWindChill d=48 m=1> reports the wind chill temperature 2 days ago
| <#RecentWindChill d=48 m=1> reports the wind chill temperature 2 days ago
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| d=n (where n runs 0 to 6) days ago; h=n (where n is any number of hours ago); m=n (where n is any number of minutes ago)
| d=n (where n runs 0 to 6) days ago; h=n (where n is any number of hours ago); m=n (where n is any number of minutes ago)
|}
|}


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


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


Note this formula uses Celsius for temperature and metres per second for wind speed. You will need to do the appropriate conversions if you use different units.  Formula is same for Cumulus 1 and MX.
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 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;
var appTempDegC = parseFloat(<#RecentOutsideTemp h=3) + (0.33 * actualVaporPress) - (0.7 * <#RecentWindSpeed h=3>) - 4;
Feels Like as implemented at version 3.6.10 (see [[#Feels_Like|Feels Like section below Current condition web tags]]) uses 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>;
else{
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
} </pre>
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
/* uses kilometres per hour for wind speed */
/*  What Cumulus MX will use to calculate apparent temperature for feels like is changed very slightly */
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;
wind_chill_mult = 1 - app_temp_mult;
FL= AT * app_temp_mult + WC * wind_chill_mult;</pre>


==Today==
==Today==
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