Feels Like - Revision history

Sfws: /* Script for doing formulae and inserting text into HTML */

2021-04-15T10:03:07Z

Script for doing formulae and inserting text into HTML

← Older revision		Revision as of 10:03, 15 April 2021
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	<pre>		<pre>
	var gust;
	switch(wind_speed_unit){
	case "mph" : gust=3.0; break;
	case "km/h" : gust=4.8; break;
	case "m/s" : gust= 1.34; break;
	case "kts" : gust=2.6 ; break;
	default : gust=0.0;
	}
	var m, n, tu = " °" + tempscale;		var m, n, tu = " °" + tempscale;
	/* are units Celsius or Fahrenheit? */		/* are units Celsius or Fahrenheit? */

Sfws: /* How to express Feels Like for highest temperatures */

2021-04-13T19:29:14Z

How to express Feels Like for highest temperatures

Sfws: /* Introduction */

2021-04-13T19:17:29Z

Introduction

← Older revision		Revision as of 19:17, 13 April 2021
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	The preferred expression varies as research into the effects of the 3 variables listed above on how temperature is perceived by bare skin on the human body continues. There has in the past been much divergence between different nations, but most now use that developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG/TI).		The preferred expression varies as research into the effects of the 3 variables listed above on how temperature is perceived by bare skin on the human body continues. There has in the past been much divergence between different nations, but most now use that developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG/TI).

	The official feels like temperature index formula of JAG/TI-2000 (temperature is measured at 1.50 metres, and wind ~~speeed~~ at 10 metres, above ground):		The official feels like temperature index formula of JAG/TI-2000 (temperature is measured at 1.50 metres, and wind speed at 10 metres, above ground):

	<~~math~~>~~G_\mathrm{J}~~ = 13.12 + 0.~~6215∗Temperature_\mathrm{~~air in Celsius} − (11.~~37∗~~(~~/text{~~wind_speed~~}_\mathrm{~~m s<sup>-1</sup>~~}∗3,~~6) ^0.16 + 0.~~3965∗Temperature_\mathrm{~~air in Celsius~~}∗(~~/~~text{~~wind_speed~~}_\mathrm{~~m s<sup>-1</sup>~~}∗3~~,6) * 2.3^0.16</~~math~~>		<tt>G = 13.12 + 0.6215 x Temperature<sub>air in Celsius</sub> − (11.37 x (wind_speed<sub>m s<sup>-1</sup></sub> x 3.6)<sup>0.16</sup> + 0.3965 x Temperature<sub>air in Celsius</sub> x (wind_speed<sub>m s<sup>-1</sup></sub> x 3,6) x 2.3<sup>0.16</sup></tt>

	Cumulus MX from version 3.6.0 fully supports (in terms of derived outputs just listed) another of the Joint Action Group for Temperature Indices (JAG/TI) formulae for '''feels like'''.		Cumulus MX from version 3.6.0 fully supports (in terms of derived outputs just listed) another of the Joint Action Group for Temperature Indices (JAG/TI) formulae for '''feels like'''.

Sfws at 18:59, 13 April 2021

2021-04-13T18:59:22Z

Show changes

Sfws: /* The various ways to express Feels Like */

2020-06-25T11:01:52Z

The various ways to express Feels Like

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 The extent to which these different expressions for feels like are supported in Cumulus varies. Not all are fully supported (fully supports means derived maxima and minima outputs are available for each day, each month, each year, monthly all time, and all-time), and none of them allow you to set alarms for when it passes a particular threshold. For example Humidity Index (Humidex) is available only for current conditions. The greatest Wind Chill (highest wind speed, lowest temperature) is available for daily, monthly, yearly, monthly-all-time, and all-time.
-The preferred expression varies as research into the effects of the 3 variables listed above on how temperature is perceived by bare skin on the human body continues. There has in the past been divergence between different nations, but most now use what Cumulus MX from version 3.6.0 fully supports (in terms of derived outputs just listed) for feels like. This is a variant on wind chill (good when temperature below 50 <sup>o</sup>F [10 <sup>o</sup>C]) and apparent temperature (good in range 20 to 28  <sup>o</sup>C), and was defined by the Joint Action Group for Temperature Indicators (JAG/TI) which is the formula used in the UK, Iceland, Australia, USA, and Canada, amongst others.
+The preferred expression varies as research into the effects of the 3 variables listed above on how temperature is perceived by bare skin on the human body continues. There has in the past been divergence between different nations, but most now use what Cumulus MX from version 3.6.0 fully supports (in terms of derived outputs just listed) for feels like. This is a variant on wind chill (good when temperature below 50 <sup>o</sup>F [10 <sup>o</sup>C]) and apparent temperature (good in range 20 to 28  <sup>o</sup>C), and was defined by the Joint Action Group for Temperature Indicators (JAG/TI) which is the formula used in the UK, Iceland, Australia, USA, and Canada, amongst others. As already mentioned MX uses same formula for what it reports as Wind Chill, and for what it reports as Feels like when temperature is below 10 °C (50 °F). Unfortunately, MX uses different formulae for Feels like when temperature is 10 °C (50 °F) or above; these formulae depend on version:
 The official formula of JAG/TI-2000 is:
 G(J) = 13,12+0,6215∗T−11,37∗(W∗3,6)0,16+0,3965∗T∗(W∗3,6)0,16(2.3) where air temperature, T, is in °C, is measured at 1.50 metres, and wind speed, W, is in m/s as measured at 10 metres.
 == Rest of this article ==

Sfws: /* New JavaScript Code required */

2020-05-31T07:46:25Z

New JavaScript Code required

← Older revision		Revision as of 07:46, 31 May 2020
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	</pre>		</pre>
	[[User:Sfws\|Sfws]] 18:53, 27 December 2012 (UTC)		[[User:Sfws\|Sfws]] 18:53, 27 December 2012 (UTC)
	[[Category:~~WebTools~~]]		[[Category:User Contributions]]
	[[Category:Terminology]]		[[Category:Terminology]]

Sfws: /* New JavaScript Code required */

2020-05-31T07:45:09Z

New JavaScript Code required

← Older revision		Revision as of 07:45, 31 May 2020
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	The class ''plots'' will need adding to the [[Stylesheet \| CSS]], it could contain the width and align clauses that you removed or any other formatting you require.		The class ''plots'' will need adding to the [[Stylesheet \| CSS]], it could contain the width and align clauses that you removed or any other formatting you require.

	= New JavaScript Code required =		== New JavaScript Code required ==

	This script introduces a number of new classes, to move styling that in the standard Cumulus ''dashboard.js'' is defined inside the script, out to an external CSS. For brevity, the list of new classes is not listed here, it is assumed you know enough to work out the list yourself, and you will probably want to use your own styling anyway.		This script introduces a number of new classes, to move styling that in the standard Cumulus ''dashboard.js'' is defined inside the script, out to an external CSS. For brevity, the list of new classes is not listed here, it is assumed you know enough to work out the list yourself, and you will probably want to use your own styling anyway.
	<pre><nowiki>/* ----------------------Apparent Temperature, Wind Chill or Heat Index-------------------*/		<pre><nowiki>/* ----------------------Apparent Temperature, Wind Chill or Heat Index-------------------*/

Sfws: /* Web implementation */

2020-05-31T07:44:24Z

Web implementation

← Older revision		Revision as of 07:44, 31 May 2020
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	= Web implementation =		= Web implementation =
	Ever thought that you want to display a 'Feels Like' temperature?

			#Want to display a 'Feels Like' temperature (and you are using a version of Cumulus that does not give you it) with a figure that is useful at all possible temperatures)?
	# Would you like to display [[Wind chill]] when it is cold and windy, [[Heat index]] when it is hot and humid, and [[Apparent temperature]] at other times?		# Would you like to display [[Wind chill]] when it is cold and windy, [[Heat index]] when it is hot and humid, and [[Apparent temperature]] at other times?
	# Do you understand how to call JavaScript code from HTML?		# Do you understand how to call JavaScript code from HTML?
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	== HTML amendment to call new script ==		== HTML amendment to call new script ==

	Supposing you stored the new script below in a file called "temperature.js" in the same directory as the calling html, then the HTML needs a call to the new script (insert just before the end of the HTML body) like this:		Supposing you stored the new script below in a file called "temperature.js" in the same directory as the calling html, then the HTML needs a call to the new script (insert just before the end of the HTML body) like this:
	<pre><script src="temperature.js"></script>		<pre><script src="temperature.js"></script>

Sfws: /* The various ways to express Feels Like */

2020-05-31T07:41:03Z

The various ways to express Feels Like

← Older revision		Revision as of 07:41, 31 May 2020
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	If you understand PHP Hypertext Preprocessor language (other languages use similar operators) you will see from this that for MX, the '''feels like''' scale follows [[Wind chill\|wind chill]] below 10 degrees Celsius, it follows [[Apparent temperature\|apparent temperature]] above 20 degrees C, and blends the proportion of each of those at in-between temperatures.		If you understand PHP Hypertext Preprocessor language (other languages use similar operators) you will see from this that for MX, the '''feels like''' scale follows [[Wind chill\|wind chill]] below 10 degrees Celsius, it follows [[Apparent temperature\|apparent temperature]] above 20 degrees C, and blends the proportion of each of those at in-between temperatures.

			The following JavaScript function will work out the feels like temperature taking as input in first parameter the current air temperature (that can be in <sup>o</sup>F or <sup>o</sup>C), the C or F is supplied in second parameter, the third parameter is the current average wind speed, the fourth parameter is the wind units (as expressed in <#windunit>), and the final parameter is the current humidity (as a %). I say current, but this function can be applied to past values as stored in standard data log. Within the function it calls other functions for calculating apparent tempewrature (AT) and wind chill (WC) and for converting temperature to Celsius (calcTempC) and converting output back to units used by Cumulus user, with rounding (calcTempR).
	The following function
	<pre>function calcFeelsLike(temp, tempLetter, wind, windUnit, RHumidity)		<pre>function calcFeelsLike(temp, tempLetter, wind, windUnit, RHumidity)
	{		{
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	return feelsLike;		return feelsLike;
	}</pre>		}</pre>

			== Rest of this article ==

	The rest of this article was written for versions of Cumulus that did not report '''JAG/TI feels like''', and uses JavaScript for deciding whether to display Heat Index, Apparent Temperature, or Wind Chill, based on the current weather conditions. It was designed to work with standard Cumulus web templates that produce HTML and do not use PHP.		The rest of this article was written for versions of Cumulus that did not report '''JAG/TI feels like''', and uses JavaScript for deciding whether to display Heat Index, Apparent Temperature, or Wind Chill, based on the current weather conditions. It was designed to work with standard Cumulus web templates that produce HTML and do not use PHP.

Sfws: /* Introduction */

2020-05-31T07:31:15Z

Introduction

@@ Line 3: / Line 3: @@
 ''Feels Like'' is a concept often quoted in weather forecasts, as the name suggests it attempts to quantify what human skin detects as the temperature, taking into account any warming or cooling effect of exposure to different humidity levels, high wind, or shade/sunshine. The best way to quantify that has been discussed in many scientific papers following on from experimentation in various laboratories, and so different formulae have been used at different times as more is learnt about how the body reacts to different conditions.
-All formulae involve the air temperature and at least one of the following:
+All formulae involve the air temperature and at least one of the following variables as well as air temperature:
 * (relative) humidity
 * wind (speed)
 * sunshine (radiation)
+{
 }</pre>

← Older revision		Revision as of 19:29, 13 April 2021
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	* There is much more divergence on what formula to use at higher temperature, reflecting that the highest temperature seen vary across the world, and because other factors like humidity also vary it is harder for Scientists to agree on what is the best way to measure effects.		* There is much more divergence on what formula to use at higher temperature, reflecting that the highest temperature seen vary across the world, and because other factors like humidity also vary it is harder for Scientists to agree on what is the best way to measure effects.
	** In the USA, a dimensionless [[Heat index]] measure is used, for temperatures above 27 °C (80 °F). The measure combines air temperature and relative humidity, and thus gives an indication of evaporation rate.		** In the USA, a dimensionless [[Heat index]] measure is used, for temperatures above 27 °C (80 °F). The measure combines air temperature and relative humidity, and thus gives an indication of evaporation rate.
	**From a very early build Cumulus used the formula exactly as defined in Wikipedia for heat index.<~~math~~>~~\mathrm{~~HI} = c_1 + c_2 T~~\text{~~°F} + c_3 R + c_4 T~~\text{~~°F} R + c_5 T^2 + c_6 RH^2 + c_7 * ~~T_\text{~~°F}^2 * RH + c_8 * ~~T_\text{~~°F} * RH^2 + c_9 * ~~T_\text{~~°F}^2 * RH^2</~~math~~>		**From a very early build Cumulus used the formula exactly as defined in Wikipedia for heat index. <tt>HI = c_1 + c_2 x T°F + c_3 x RH + c_4 x T°F x R + c_5 x T<sup>2</sup> + c_6 RH<sup>2</sup> + c_7 x T°F<sup>2</sup> x RH + c_8 x T°F x RH<sup>2</sup> + c_9 x T°F<sup>2</sup> x RH<sup>2</sup></tt>
	***This was improved from version 1.9.0 (11 Sept 2010) in Cumulus 1 with a new formula covering a greater range of humidities accurately. Steve Loft did not document this change, however his MX beta source (as handed over to the community) uses Rothfusz adjustments to reduce the index reported if the relative humidity is below 13%, and he stated he created MX beta from a machine-level translation of Cumulus 1.9.4.		***This was improved from version 1.9.0 (11 Sept 2010) in Cumulus 1 with a new formula covering a greater range of humidities accurately. Steve Loft did not document this change, however his MX beta source (as handed over to the community) uses Rothfusz adjustments to reduce the index reported if the relative humidity is below 13%, and he stated he created MX beta from a machine-level translation of Cumulus 1.9.4.
	***The current MX release has not changed that MX beta code, it uses a minimum of 80 <sup>o</sup>Fahrenheit air temperature cut-off in MX, and on the assumption that this measure is only of interest in USA, the calculation is entirely done in Fahrenheit. Mark did remove any temperature conversion of output.		***The current MX release has not changed that MX beta code, it uses a minimum of 80 <sup>o</sup>Fahrenheit air temperature cut-off in MX, and on the assumption that this measure is only of interest in USA, the calculation is entirely done in Fahrenheit. Mark did remove any temperature conversion of output.
	*** In the UK, with its cooler climate, some people use a modified formula for Heat Index with the cut-off revised to 20 <sup>o</sup>Celsius (68 <sup>o</sup>Fahrenheit). (All Cumulus releases, for temperatures below 80 <sup>o</sup>Fahrenheit, will show the air temperature wherever Heat Index would appear).		*** In the UK, with its cooler climate, some people use a modified formula for Heat Index with the cut-off revised to 20 <sup>o</sup>Celsius (68 <sup>o</sup>Fahrenheit). (All Cumulus releases, for temperatures below 80 <sup>o</sup>Fahrenheit, will show the air temperature wherever Heat Index would appear).
	** In Canada, [[Humidex\|Humidity Index]] also combines the effects of heat and humidity. The actual formula involves air temperature and dew point:		** In Canada, [[Humidex\|Humidity Index]] also combines the effects of heat and humidity. The actual formula involves air temperature and dew point:
	<~~math~~>~~\text{~~Humidity Index} = ~~Temperature_\mathrm{~~air_in_Celsius} + ~~\frac{5}{9}~~ ~~\left[~~6.11~~\times~~ 2.71828^{5417.7530 ~~\left(\frac{1}{273~~.16} - ~~\frac{1}{273~~.15+~~T_\text~~{dew_in_Celsius~~}}\right)}~~ - 10~~\right]~~</~~math~~>		<tt>Humidity Index = Temperature<sup>air_in_Celsius</sup> + 5÷9 x 6.11 x 2.71828<sup>5417.7530</sup> x 1÷273.16 - 1÷273.15 + T<sup>{dew_in_Celsius</sup> - 10</tt>

	:5417.7530 is a rounded constant based on the molecular weight of water, [[Enthalpy of vaporization\|latent heat of evaporation]], and the [[universal gas constant]]. The humidity adjustment approximately amounts to one Fahrenheit degree for every millibar by which the [[Vapour pressure of water\|partial pressure of water]] in the atmosphere exceeds ~~{{convert\|~~10\|mb}}.		:5417.7530 is a rounded constant based on the molecular weight of water, Enthalpy of vaporization\|latent heat of evaporation, and the universal gas constant. The humidity adjustment approximately amounts to one Fahrenheit degree for every millibar by which the Vapour pressure of water(partial pressure of water) in the atmosphere exceeds 10 mb.

	** In Australia, [[Apparent temperature]] uses a mathematical model of the effects of temperature, humidity, wind speed, and (optionally) solar radiation.		** In Australia, [[Apparent temperature]] uses a mathematical model of the effects of temperature, humidity, wind speed, and (optionally) solar radiation.
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	***All releases of MX use that same formula for any output labelled '''Apparent Temperature'''.		***All releases of MX use that same formula for any output labelled '''Apparent Temperature'''.
	*** There are many alternative formulae for calculating the vapour pressure of water, so there is a certain lack of consistency in how any '''Feels Like Temperature''' based on ''Apparent Temperature'' is reported. Cumulus MX has tried various formulas for calculating vapour pressure.		*** There are many alternative formulae for calculating the vapour pressure of water, so there is a certain lack of consistency in how any '''Feels Like Temperature''' based on ''Apparent Temperature'' is reported. Cumulus MX has tried various formulas for calculating vapour pressure.
	***For versions 3.5.4 (25 Apr 2020 build 3075) to version 3.6.7 (4 June 2020 build 3083) of MX used a different formula for water vapour to that used for version 3.6.8 build 3084. These differences affected the calculation these releases did for '''Feels Like Temperature''' at higher air temperatures. Because these have been ~~superceded~~, I have deleted the formula that was quoted here.		***For versions 3.5.4 (25 Apr 2020 build 3075) to version 3.6.7 (4 June 2020 build 3083) of MX used a different formula for water vapour to that used for version 3.6.8 build 3084. These differences affected the calculation these releases did for '''Feels Like Temperature''' at higher air temperatures. Because these have been superseded, I have deleted the formula that was quoted here.

	===How to express '''Feels Like''' when air temperature is above 20 <sup>o</sup>Celsius (68 <sup>o</sup>Fahrenheit)===		===How to express '''Feels Like''' when air temperature is above 20 <sup>o</sup>Celsius (68 <sup>o</sup>Fahrenheit)===
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	** For versions 3.5.4 (25 Apr 2020 build 3075) to version 3.6.7 (4 June 2020 build 3083) of MX used a different formula for water vapour to that used for version 3.6.8 build 3084. These differences affected the calculation these releases did for '''Feels Like Temperature''' in this temperature range.		** For versions 3.5.4 (25 Apr 2020 build 3075) to version 3.6.7 (4 June 2020 build 3083) of MX used a different formula for water vapour to that used for version 3.6.8 build 3084. These differences affected the calculation these releases did for '''Feels Like Temperature''' in this temperature range.
	** From Cumulus release version 3.6.10 build 3086, the apparent temperature element (before weighting) is based on the same formula as used to report 'Apparent Temperature'.		** From Cumulus release version 3.6.10 build 3086, the apparent temperature element (before weighting) is based on the same formula as used to report 'Apparent Temperature'.


	=Support for these derivived parameters in daily extremes, monthly extremes, yearly extremes, all-time extremes, and monthly all-time extremes=		=Support for these derivived parameters in daily extremes, monthly extremes, yearly extremes, all-time extremes, and monthly all-time extremes=