Feels Like: Difference between revisions

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1,409 bytes added ,  27 May 2013
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(This code was originally posted as a comment to enhancement request number 52)
 
=Introduction=
''Feels Like'' is a concept often quoted in weather forecasts, as the name suggests it attempts to quantify what a human detects as the warming or cooling effect.
A number of formulae are used, all involve the air temperature and at least one of the following:
* (relative) humidity
* wind (speed)
* sunshine (radiation)
Look up [[Apparent_temperature]], [[Heat_index]], [[Humidex]], or [[Wind_chill]].
Davis stations also provide [[Webtags#Davis | THWindex and THWSindex ]]
= Web implementation =
Ever thought that you want to display a 'Feels Like' temperature?
 
# 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?
 
# Can you modify a Cascading [[Stylesheets]] (CSS) file to include new classes to define the appearance of various items?
Do you understand how to call JavaScript code from HTML?
 
Can you modify a Cascading [[Stylesheets]] (CSS) file to include new classes to define the appearance of various items?
 
If you can answer yes to all these questions, the following JavaScript code may be useful to you. Depending on the element id that it finds on your HTML page, it either inserts an appropriate 'Feels Like temperature' as a figure, or it draws up a temperature bar graph in the standard Cumulus style, but shows the current value for a parameter selected depending on the current conditions (although it also draws any maximum and/or minimum values of that parameter that are available).
 
You need to include something like the script that appears at the bottom of the standard gaugesT.htm in respect of defining temperature, humidity and wind speed:
==HTML code to translate web tags to JavaScript variables (as modified for additional parameters)==
==HTML code==
<pre><script>/* -------------------------------- Convert Cumulus tags into Javascript variables for selecting 'Feels Like' parameter------------------------------------- */
var tempscale= "<#tempunitnodeg>"; // This is temperature unit, it contains F or C (without the HTML code for degree because JavaScript cannot understand it)
var ExtraSensor2Name = ""; /* Extra temperature/humidity sensor two name prefix */
var tempex2 = new Array("","","","");/* EXTRA TEMPERATURE TWO parameters (required even if not used) */
var TempColor = ""; // If set defines the bar chart column colour for dewpointstandard (otherCumulus colourscharts setlike within javascript)dewpoint
var tempdp = new Array("<#dew>","<#dewpointTL>","<#dewpointTH>","","");/* DEW POINT (current, today low, today high) */
var tempapp = new Array("<#apptemp>","<#apptempTL>","<#apptempTH>","","");/* APPARENT TEMPERATURE (current, today low, today high)*/
var tempis = new Array("not used","","","");/* INDOOR TEMPERATURE (not used by feels like routine) */
var humos = new Array("<#hum>","<#humTL>","<#ThumTL>","<#humTH>", "<#ThumTH>");/* OUTSIDE HUMIDITY latest, minimum, time of minimum, maximum, time of maximum*/
// Wind histogram data (Modified from Cumulus original - needs more work as degree symbol giving warning messages on validation for HTML5)
var winddata = new Array("<#wgust>","<#bearing>","<#wspeed>","<#avgbearing>","<#wgustTM>", "<#windunit>", "<#bearingTM>&#176; at <#TwgustTM>");/* WIND SPEEDS (latest gust, its bearing, average wind speed, average bearing, maximum gust today, unit for wind speeds, bearing of maximum gust today with symbol for degrees, time of maximum gust) */
</script></pre>
== HTML amendment to call new script ==
The HTML also needs a call to the following script (insert just before the end of the HTML body, and an element id for determining where the script inserts the Feels Like data.
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 script below in a file called "temperature.js", then the call would look like this:
<pre><script src="temperature.js"></script>
</body></pre>
== Defining HTML insert position ==
The HTML needs an element id for determining where the script inserts the Feels Like data.
=== Option 1 - Modifying a table to display a figure ===
[[File:Feels_like_numerical.png|200px|thumb|left|set of values]]
The element id shown below would result in the numerical value being inserted as per screen image on left. Moving your mouse over the figure would display the information about the parameter being shown. This could be suitable for your 'now' page (the standard Cumulus indexT.htm displays wind chill, heat index and apparent temperature, but maybe you want to alter that? (Note this element id is not relevant to the gauges page, unless you want to display numerical values without a graphic).
== HTML table rows to replace ==
<pre><div id="variable_figure" class="p1 labels" title="'Feels Like' - need to have JavaScript enabled for automatic selection of parameter to show here">
<pre><tr class="td_temperature_data">
<small>Feels Like (title varies)</small> <br><!-- insert position for variable numerical value --></pre>
<td>Windchill</td>
 
<td><#wchill>&nbsp;<#tempunit></td>
Perhaps you use the standard gaugesT.htm template, but want to change it so it displays an appropriate Feels Like graphic (see next screen shot)?
<td>Humidity</td>
<td><#hum>%</td>
</tr>
<tr class="td_temperature_data">
<td>Heat Index</td>
<td><#heatindex>&nbsp;<#tempunit></td>
<td>Apparent Temperature</td>
<td><#apptemp>&nbsp;<#tempunit></td>
</tr></pre>
== HTML code required for inserting figure ==
<pre><tr class="td_temperature_data"><td colspan="4" id="variable_figure" title="'Feels Like' - need to have JavaScript enabled for automatic selection of parameter to show here">
<small>Feels Like (title varies)</small> <br><!-- insert position for variable numerical value --></td></tr></pre>
=== Option 2 - Modifying the Gauges page to display a different bar chart ===
Perhaps you use the standard gaugesT.htm template, but want to change it so it displays an appropriate Feels Like graphic (see screen shot)?
[[File:Feels_like_graphic.png|50px|thumb|left|bar chart]]
Then you need to note the differences between the temperature and wind histogram data transfer shown above and that appearing at the foot of the standard Cumulus page. If you are able to cope with the necessary coding changes, you could replace the following code with the code that follows it (but there may be sizing issues to sort out).
== HTML code for Inside Temperature can be replaced ==
<pre><td width="33%" align="center" bgcolor="#EFEFEF"><div id="insidetemp">small</div></td></pre>
== HTML code required for varying chart ==
<pre><td class="plots"><div id="feels_like"></div></td></pre>
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.
==JavaScript Code==
= New JavaScript Code required =
<pre><nowiki>/* ----------------------Apparent Temperature, Wind Chill or Heat Index-------------------*/
 
// --- variables required ---
 
var gauges_images=”dbimages”; // directory where temperature scale image is stored
 
var divid = new Array("outsidetemp","apptemp","dewpoint","heatindex","windchill","windchill/heatindex");var ddata = new Array(tempos, tempapp, tempdp, temphi, tempwc);var dColour = new Array("#c60","#f90","sienna","purple","cyan");var esn1 = "Extra Temperature 1";var esn2 = "Extra Temperature 2";if(ExtraSensor1Name) esn1 = ExtraSensor1Name + " Temperature";if(ExtraSensor2Name) esn2 = ExtraSensor2Name + " Temperature";var divti = new Array("Outside Temperature","Apparent Temperature",esn1,esn2,"Dew Point","Heat Index","Wind Chill");
 
var dtext =new Array("This routine automatically decides which parameter best represents the 'Feels Like' temperature by checking the maximum wind gust speed and the minimum and maximum temperature for this meteorological day.: These are used to pick between 'Wind Chill' (low minimum temperature, high wind gust), 'Heat Index' (high maximum temperature, ) and 'Apparent Temperature' (all other cases).",
 
"The (USA) Heat Index only applies if the actual temperature is at or above 27 °C (80 °F) and relative humidity peaks above 40% .: The index modifies air temperature using relative humidity in an attempt to determine the human-perceived equivalent temperature (how hot it feels).",
 
"Wind Chill Temperature only applies for temperatures at or below 10 °C (50 °F) and wind speeds above 3.0 mph (4.8 kilometres per hour, 1.34 metres per second, or 2.6 knots) (it is selected if the outdoor temperature today is or has fallen below 10.5, 51 respectively and today's maximum measured gust has exceeded quoted figure).: Wind Chill modifies air temperature using wind speed in an attempt to determine the exposed skin-perceived equivalent temperature (how cold it feels).");//---------------------------------------------------------------function dovariablebarchart(eidh){
//---------------------------------------------------------------
 
function dovariablebarchart(eidh){
var m, n, mo=[], tu = "°" + tempscale;
 
/*-- some javascript code that inserts 'Apparent Temperature' normally; but replaces that with 'Wind Chill' if minimum temperature is below 12 degrees Celsius, or replaces it with 'Heat Index' if maximum temperature is above 24 degrees Celsius */
 
/* are units Celsius or Fahrenheit? */
 
if(tempscale=="C"){ // Celsius
 
n= 10.5; // wind chill
 
m = 27; // heat index
 
}else{ // Fahrenheit
n = 51; // wind chill
 
m = 80; // heat index
n = 51;
 
m = 80;
 
}
 
var gust;
 
switch(winddata[5]){
 
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 motext = dtext[1];var modata = ddata[1];var selectid = divid[1];var selectColour = dColour[1];var tit=divti[1];// apparent is default plot
 
if((tempos[2] > m) && (humos[3] > 40)) { // check maximum
motext = dtext[2];modata = ddata[3];selectid = divid[3];selectColour = dColour[3];tit=divti[5]; //heat index plot
 
} else if ((tempos[1] <n) && (gust < winddata[4])) { // check minimum temp and maximum wind gust
 
motext = dtext[3];modata = ddata[4];selectid = divid[4];selectColour = dColour[4];tit=divti[6]; // wind chill plot
 
}// end of if else group checking minimum and maximum temperatures
 
mo[0]=dtext[0];eidh.title ="header=["+'<img class="vam" src="'+gauges_images+'/information.png" alt=" graphic with little i representing information">'+"Feels Like ("+tu+")] body=["+getmo(mo)+"]";eidh.innerHTML += tit;// variable title written, check if summary page, if so appropriate figure is required and heading box requires a title
 
if(document.getElementById("variable_figure")){eidw=document.getElementById("variable_figure");n=modata[1];if(!isNaN(n)){ // check if minimum measurement is available
 
n =", "+"Min="+modata[1] + " °" + tempscale;} else {n="";}m=modata[2];if(!isNaN(m)){ // check if maximum measurement is available
m =", "+"Max="+modata[2] + " °" + tempscale;} else {m="";}eidw.innerHTML=("Latest="+modata[0] + " °" + tempscale+n+m);mo[0]=motext;eidw.title="header=["+'<img class="vam" src="'+gauges_images+'/information.png" alt=" graphic with little i representing information">'+tit+" ("+tu+")] body=["+getmo(mo)+"]";} // end of summary page coding
 
// rest of function only followed if bar chart to be drawn
 
if(document.getElementById("windchill/heatindex")){eidw=document.getElementById("windchill/heatindex");var size=eidw.innerHTMLdotemps(tit,selectid,eidw,size,modata, motext, selectColour);}} // end of function
 
//------------------------------------------------------------------------------
 
//variables for mouseover popup
 
var mod =0;//mouseover popup delay (msecs))
 
var fst = "position:relative; cursor:pointer; ";
 
var tds = "font-family: Verdana,Arial,Helvetica; font-size: 9px; color: #000055; "
 
 
//------------------------------------------------------------------------------
 
 
/* COMMON SUBROUTINE used by ALL CALLS FOR MOUSE OVER TEXT to create body table when using BOXOVER script */
 
 
function getmo(mot){
 
// Based on script included with Cumulus, but modified to use classes to refer to external Cascading Style Sheet instead of style attributes embedded in script – see comments that follow
 
var st = " ";
st += "<table class='b_green cmo'>"; // defines a background colour
 
for (var j=0;j<mot.length;j++){
>st += "<table class='b_green cmo'>"; // defines a background colour
 
var j;
 
for (j=0;j<mot.length;j++){
 
st += "<tr><td class='labels'>"; // for example labels could be bold and have a background colour
 
st += mot[j].substring(0,mot[j].indexOf(":")+1); // Extract string up to colon into first cell of row
 
 
st += "</td><td class='site-data'>";// numbers are centered or whatever suits you
 
st += mot[j].substring(mot[j].indexOf(":")+1); // Extract string after colon into second cell of row
 
st += "</td></tr>";
 
}
 
st += "</table>";
 
return st;
 
}
 
//------------------------------------------------------------------------------
 
 
/* ------------------------ ALL TEMPERATURE BASED BAR CHARTS ------------------ */
 
 
function dotemps(tit,id,eid,size,data, text, nowColour){
 
var tgd,factor, bottom, scale, maxm, t, h, l, r, tu, val, fst= "position:relative; cursor:pointer; ";
 
if(size=="small"){
 
tgd="<div id='"+id+"' style='"+fst+"width:90px;'><img
 
src='”+gauges_images+”/thermos.gif''></div>”;
 
factor=2;
 
bottom=195;
 
}else{
 
tgd="<div id='"+id+"' style='"+fst+"width:90px;'><img src='”+gauges_images+”/thermol.gif'></div>";
 
factor=1;
 
bottom=375;
 
}
 
eid.parentNode.innerHTML=tgd;
 
eid=document.getElementById(id);
 
tu = "°" + tempscale;
 
if(tempscale=="C"){ // Celsius
 
scale=3.6/factor;
 
maxm=60;
 
}else{ // Fahrenheit
 
scale=2/factor;
 
maxm=140;
 
}
 
var valnow= parseFloat(data[0]);
 
t=parseInt(((maxm - valnow) * scale)+16);
 
h=(bottom-t)+1;// calculate length of column (origin is top left, so draw downwards)
 
l=25; // left hand end of horizontal lines for maximum
 
r=66; // right hand end of horizontal lines for minimum
 
// Other end of horizontal lines for maximum and minimum set at 45 - Modified so lines do not overlap and always show
 
var jg=new jsGraphics(id);
 
jg.setColor(nowColour || "#cc9"); // column fill colour taken from either calling code or default here
 
var mo = new Array()
 
var c = 0;
 
mo[c]=text; // descriptive text re observation or calculation
 
c++; // increment array index
 
if(!isNaN(t)){ // check if measurement is numerical
 
jg.fillEllipse(36,(bottom-16),20,20); // bulb of thermonmeter added by SFWS
 
jg.fillRect(41,t,9,h); // left and width of column plot are constants
 
mo[c]="<span class='sienna'>Current:</span>"+valnow+" "+tu; // semi-colon separates cells of table
 
} else mo[c]="Current temperature: Not Available"; // colon separates cells of table
 
c++;
if(data[1]){ // if minimum available
 
if(data[1]){
 
jg.setColor("navy");
 
jg.setStroke(2);
 
val= parseFloat(data[1]);
 
t=parseInt(((maxm - val)*scale)+16);
 
if(!isNaN(t))jg.drawLine(45,t,r,t);
 
mo[c]="<span class='navy'>Minimum This Meteorological Day:</span>"+val+" "+tu;
 
c++;
 
}
if(data[2]){ // if maximum available
 
 
if(data[2]){
 
jg.setColor("red");
 
jg.setStroke(2);
 
val=parseFloat(data[2]);
 
t=parseInt(((maxm - val)*scale)+16);
 
if(!isNaN(t))jg.drawLine(l,t,45,t);
 
mo[c]="<span class='red'>Maximum This Meteorological Day:</span>"+val+" "+tu;
 
c++;
 
if(tempscale=="C"){
 
val=Math.round((parseFloat(data[2])*1.8)+32)
 
mo[c]="<span class='red'>Maximum after conversion:</span>"+val+" "+"°" +"Farenheit";
 
c++;
 
}
 
}
if(data[3]){ // if trend available
 
jg.drawImage('gauges_images/'+data[4]+'.gif',41,8,9,29);// Modified (different rising/falling images and different position so trend visible at top!) data[4] is fixed text to determine filename
if(data[3]){
 
jg.drawImage('gauges_images/'+data[4]+'.gif',41,8,9,29);// Modified by Sele Farm Weather Station (different rising/falling images and different position so trend visible at top!) data[4] is fixed text to determine filename
 
mo[c]="Trend:"+data[3];// data[3] uses text that can be set in 'samplestrings.ini'
 
}
 
 
jg.paint();
 
eid.title="header=["+'<img class="vam" src="'+gauges_images+'/information.png" alt=" graphic with little i representing information">'+tit+" ("+tu+")] body=["+getmo(mo)+"]";
 
}
 
 
/* -------------------------------------------------------------------------------------------
 
Note that the code works for all temperature and wind speed units permitted by Cumulus, 'variable_figure' is id for HTML where numbers to be written (perhaps on indexT.htm template page) and "feels_like" is id for HTML element where graphic to be drawn (normally on gaugesT.htm template page)
 
------------------------------------------------------ */
// --- tabular display ---
 
if(document.getElementById("variable_figure")){
 
eidh=document.getElementById("variable_figure");
 
// call subroutine that determines which figures are to be displayed
 
dovariablebarchart(eidh)
 
}
// --- multipurpose bar chart ---
 
// --- multipurpose bar chart --------
 
if(document.getElementById("feels_like")){
 
eidh=document.getElementById("feels_like");
 
// call subroutine that determines which bar chart is to be plotted
 
dovariablebarchart(eidh)
 
}</nowiki>
</pre>
 
[[User:Sfws|Sfws]] 18:53, 27 December 2012 (UTC)
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