Temperature (and humidity) measurement - Revision history

Sfws: /* How Cumulus software handles Temperature and Humidity */

2021-07-31T19:49:14Z

How Cumulus software handles Temperature and Humidity

← Older revision		Revision as of 19:49, 31 July 2021
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	=How Cumulus software handles Temperature and Humidity=		=How Cumulus software handles Temperature and Humidity=
			Cumulus expects all stations to report a minimum number of parameters including outside temperature and relative humidity. Some weather station types also report wind chill, dew-point temperature, and other derivatives related to temperature and/or relative humidity. Cumulus is able to calculate wind chill, dew-point, and other derivatives (and if any of these are available from your station, you can choose whether to use the value from station or the value Cumulus calculates).
⚫	The type of weather station used determines which parameters are reported by that station and which need to be calculated by Cumulus. If Cumulus 1 is using temperature in a calculation of parameters like dew-point or apparent temperature, then for most stations it will apply any calibration settings to the temperature read from the station before using it in that calculation. Similarly if humidity is read from the station, the calibrated value is used in subsequent calculations. See the support forum for further information e.g. for Instromet stations, Cumulus 1 calculates the relative humidity from the reported wet bulb, and dry bulb, temperatures, the uncalibrated values of temperature and (calculated) humidity are then used to calculate dew-point.

			If Cumulus (1 or MX) is using "outside temperature" in a calculation of parameters like dew-point, or apparent temperature, then for most stations it will apply any calibration settings to the temperature read from the station before using it in that calculation. In Cumulus 1, uncalibrated temperature values are used from Instromet, see support forum for more details.

		⚫	Similarly if humidity is read from the station, the calibrated value is used in subsequent calculations. See the support forum for further information e.g. '''for Instromet stations''', Cumulus 1 ''calculates the relative humidity from the reported wet bulb, and dry bulb'', temperatures, the uncalibrated values of temperature and (calculated) humidity are then used to calculate dew-point.

	== Logged values ==		== Logged values ==
	At the logging interval you set, Cumulus logs outdoor temperature, dew-point, and relative humidity; plus a whole host of values derived from them (and from wind speed), in [[Standard_log_files]], with separate files for each month.		At the logging interval you set, Cumulus logs outdoor temperature, dew-point, and relative humidity; plus a whole host of values derived from them (and from wind speed), in [[Standard_log_files]], with separate files for each month.

	Optionally, measurements from extra sensors can be logged in [[Extra_Sensor_Files\| extra monthly files]].		Optionally, measurements from extra sensors can be logged in [[Extra_Sensor_Files\| extra monthly files]]. For Oregon Scientific stations, temperature readings from one extra sensor can optionally replace the main sensor for "outdoor temperature", see [[Webtags#Web_tags_mentioning_.28outside.29_temperature\|here]]for details.

	Optionally, but only in Cumulus 1, indoor measurements can be logged in [[speciallog.txt\|a special ongoing log]].		Optionally, but only in Cumulus 1, indoor measurements can be logged in [[speciallog.txt\|a special ongoing log]].

			From release 3.12.0, MX maintains a [[Cumulusmx.db\|database table]] that can hold temperatures at one (assuming MX has been left running) minute intervals for the last 7 days.

	==Cumulus Calculated Parameters==		==Cumulus Calculated Parameters==
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	}</pre>		}</pre>

	Note this means that Cumulus 1 and MX log files have a continuity break when you migrate from one flavour to another.		Note this means that Cumulus 1 and MX log files have a continuity break in dew point values when you migrate from one flavour to another.



	[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]

	[[Apparent temperature]]

	It uses a formula from the Australian BOM - http://www.bom.gov.au/info/thermal_stress/#atapproximation

			Look up [[Humidex]], [[Wind chill]], [[Heat index]], [[Apparent temperature]], [[Feels Like\|Feels Like temperature]], [[Heat/cold degree days and Chill hours]], [[Average temperature]],
	Note that the version used is the one that doesn't take into account solar radiation.
		⚫	[[Extra_Sensor_Files\|Extra temperatures]] for details about the various derivatives.

	[[Heat/cold degree days and Chill hours]]

	[[Average temperature]]

⚫	[[Extra_Sensor_Files\|Extra temperatures]]

	<br>
	[[Category:Terminology]]		[[Category:Terminology]]
			History:
	<br>
	[[User:Sfws\|Sfws]] 00:34, 29 November 2012 (UTC)		* Created: [[User:Sfws\|Sfws]] 00:34, 29 November 2012 (UTC) for legacy Cumulus
			* Amended: [[User:Sfws\|Sfws]] ([[User talk:Sfws\|talk]]) 19:49, 31 July 2021 (UTC) to also cover MX as at 3.12.0

Sfws: /* Cumulus Calculated Parameters */

2020-06-14T08:20:20Z

Cumulus Calculated Parameters

← Older revision		Revision as of 08:20, 14 June 2020
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	<pre>public static double DewPoint(double tempC, double humidity)		<pre>public static double DewPoint(double tempC, double humidity)
	{		{
	//return tempC + ((0.13tempC) + 13.6)Math.Log(humidity/100.0);
	// Davis algorithm
	double lnVapor = Math.Log(ActualVapourPressure(tempC, (int) humidity));		double lnVapor = Math.Log(ActualVapourPressure(tempC, (int) humidity));
	return ((243.12 * lnVapor) - 440.1) / (19.43 - lnVapor);		return ((243.12 * lnVapor) - 440.1) / (19.43 - lnVapor);

Sfws: /* Cumulus Calculated Parameters */

2020-06-14T08:19:35Z

Cumulus Calculated Parameters

@@ Line 82: / Line 82: @@
 ==Cumulus Calculated Parameters==
 See external Wiki or other sections of this Wiki for specific information on the values that Cumulus calculates:
@@ Line 89: / Line 90: @@
 *The dew point calculation for Cumulus 1 uses a third party library which uses the Davis dew point calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''
-* The dew point calculation for MX follows the standard [https://en.wikipedia.org/wiki/Dew_point calculation in wikipedia].
+* The dew point calculation for MX follows the standard [https://en.wikipedia.org/wiki/Dew_point calculation in wikipedia]
 Note this means that Cumulus 1 and MX log files have a continuity break when you migrate from one flavour to another.

Sfws: /* Cumulus Calculated Parameters */ dew point

2020-06-13T22:16:18Z

Cumulus Calculated Parameters: dew point

← Older revision		Revision as of 22:16, 13 June 2020
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	[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb]		[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb]

		⚫	and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]]
⚫	~~and~~ [https://en.wikipedia.org/wiki/Dew_point ~~Dew point]~~

		⚫	The dew point calculation for Cumulus 1 uses a third party library which uses the Davis dew point calculation '''dewpoint := tempinC + ((0.13 tempinC) + 13.6) * Ln(humidity / 100)'''
			* The dew point calculation for MX follows the standard [https://en.wikipedia.org/wiki/Dew_point calculation in wikipedia].

			Note this means that Cumulus 1 and MX log files have a continuity break when you migrate from one flavour to another.
			<pre>
			/* =================================================================================================
			DEW POINT TEMPERATURE
			The dew point calculation in Cumulus 1 uses a third party library which uses the Davis dew point calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''
			============================================================================== */
			function calcDewPoint(tempDegC, tempLetter, RHumidity)
			{
			var dp = tempDegC + ((0.13 * tempDegC) +13.6) * Math.log(RHumidity / 100);
			return calcTempR(dp, tempLetter); // return as string in right units for user
			}
			/* =================================================================================================
			DEW POINT TEMPERATURE
			The following is a formula from https://github.com/nicolasgrancher/weather-js/blob/master/js/weather.js
			This matches the formula that MX uses.
			It has only been edited to add the middle input parameter and to output using a call to CalcTempR
			============================================================================== */
			/**
			* Dew point calculation.
		⚫	* @see https://en.wikipedia.org/wiki/Dew_point
			*
			* @param Tc temperature in celsius
			* @param R relative humidity
			* @returns {number}
			*/
			function dewPoint(Tc, tempLetter, R)
			{ // parameters: tempDegC, tempLetter, (RHumidity /100) // added middle parameter, should be accessible anyway, but playing safe
			if (Tc < 0 \|\| Tc > 60)
			{
			return calcTempR(Tc, tempLetter); // return as string in right units for user
			}

			if (R < 0.01 \|\| R > 1) {
			return calcTempR(Tc, tempLetter); // return as string in right units for user
			}

			var a = 17.27;
			var b = 237.7;

			var alphaTR = ((a * Tc) / (b + Tc)) + Math.log(R);

			var Tr = (b * alphaTR) / (a - alphaTR);

			if (Tr < 0 \|\| Tr > 50) {
			return calcTempR(Tc, tempLetter); // return as string in right units for user
			}

			return calcTempR(Tr, tempLetter); // return as string in right units for user
			}
			</pre>

⚫	and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]]

⚫	The dew point calculation uses a third party library which uses the Davis dew point calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''

	[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]		[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]

Sfws: /* Cumulus Calculated Parameters */

2020-06-13T08:50:14Z

Cumulus Calculated Parameters

← Older revision		Revision as of 08:50, 13 June 2020
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	See external Wiki or other sections of this Wiki for specific information on the values that Cumulus calculates:		See external Wiki or other sections of this Wiki for specific information on the values that Cumulus calculates:

	[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb ~~and Dew point] and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]~~]		[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb]

			and [https://en.wikipedia.org/wiki/Dew_point Dew point]
⚫	The ~~dewpoint~~ calculation uses a third party library which uses the Davis ~~dewpoint~~ calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''

			and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]]

		⚫	The dew point calculation uses a third party library which uses the Davis dew point calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''

	[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]		[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]

Sfws: /* Logged values */

2020-06-09T15:16:28Z

Logged values

← Older revision		Revision as of 15:16, 9 June 2020
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	The type of weather station used determines which parameters are reported by that station and which need to be calculated by Cumulus. If Cumulus 1 is using temperature in a calculation of parameters like dew-point or apparent temperature, then for most stations it will apply any calibration settings to the temperature read from the station before using it in that calculation. Similarly if humidity is read from the station, the calibrated value is used in subsequent calculations. See the support forum for further information e.g. for Instromet stations, Cumulus 1 calculates the relative humidity from the reported wet bulb, and dry bulb, temperatures, the uncalibrated values of temperature and (calculated) humidity are then used to calculate dew-point.		The type of weather station used determines which parameters are reported by that station and which need to be calculated by Cumulus. If Cumulus 1 is using temperature in a calculation of parameters like dew-point or apparent temperature, then for most stations it will apply any calibration settings to the temperature read from the station before using it in that calculation. Similarly if humidity is read from the station, the calibrated value is used in subsequent calculations. See the support forum for further information e.g. for Instromet stations, Cumulus 1 calculates the relative humidity from the reported wet bulb, and dry bulb, temperatures, the uncalibrated values of temperature and (calculated) humidity are then used to calculate dew-point.
	== Logged values ==		== Logged values ==
	At the logging interval you set, Cumulus logs outdoor temperature, dew-point, and relative humidity in [[~~Monthly_log_files\|~~separate files for each month]].		At the logging interval you set, Cumulus logs outdoor temperature, dew-point, and relative humidity; plus a whole host of values derived from them (and from wind speed), in [[Standard_log_files]], with separate files for each month.

	Optionally, measurements from extra sensors can be logged in [[Extra_Sensor_Files\| extra monthly files]].		Optionally, measurements from extra sensors can be logged in [[Extra_Sensor_Files\| extra monthly files]].

	Optionally, indoor measurements can be logged in [[speciallog.txt\|a special ongoing log]].		Optionally, but only in Cumulus 1, indoor measurements can be logged in [[speciallog.txt\|a special ongoing log]].

	==Cumulus Calculated Parameters==		==Cumulus Calculated Parameters==

Sfws: /* Celsius */

2020-06-09T15:13:59Z

Celsius

← Older revision		Revision as of 15:13, 9 June 2020
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	ANDERS CELSIUS SCALE: Anders defined 0 on his Celsius scale as the boiling point of water and 100 on his scale as the freezing point of water. Carolus Linnaeus (1707 to 1778) in 1744 (after the death of Anders Celsius) reversed that Celsius scale, to the order we know now. Various other people are also credited with developing what was known under various names and became known in the 19th Century as the Centigrade scale.		ANDERS CELSIUS SCALE: Anders defined 0 on his Celsius scale as the boiling point of water and 100 on his scale as the freezing point of water. Carolus Linnaeus (1707 to 1778) in 1744 (after the death of Anders Celsius) reversed that Celsius scale, to the order we know now. Various other people are also credited with developing what was known under various names and became known in the 19th Century as the Centigrade scale.

	CENTIGRADE: Zero Centigrade is the freezing point of water and 100 units from there is water's boiling point at a pressure of one standard atmosphere. Jean-Pierre Christin in 1743 independently developed a temperature scale with zero for water's freezing point and 100 for water's boiling point and in May of that year he published the design of a thermometer by a craftsman in Lyon using this scale. The temperature scale 'in 100 steps' or in Latin 'centum gradus' (anglicised as Centigrade) officially ceased to exist in 1948, when the unit became degrees Celsius. Older people still use the term Centigrade sometimes in the temperature measuring context, outside the Spanish- and French-speaking world where grad applies to angular measurement (and centigrade is equivalent to 0.009 angular degrees - angular degrees is the unit where 360 is one rotation).		CENTIGRADE: Zero Centigrade is the freezing point of water and 100 units from there is water's boiling point at a pressure of one standard atmosphere. Jean-Pierre Christin in 1743 independently developed a temperature scale with zero for water's freezing point and 100 for water's boiling point and in May of that year he published the design of a thermometer by a craftsman in Lyon using this scale.
			*The temperature scale 'in 100 steps' or in Latin 'centum gradus' (anglicised as Centigrade) officially ceased to exist in 1948, when the unit became degrees Celsius.
			*This terminology is not used in the Spanish- and French-speaking world where grad applies to angular measurement (and centigrade is equivalent to 0.009 angular degrees - angular degrees is the unit where 360 is one rotation).
			*Older people still use the term Centigrade sometimes in the temperature measuring context.
			*Centigrade is often quoted by TV journalists, in the UK anyway, despite them being born after 1948!

	=Instruments=		=Instruments=

Sfws: /* Fahrenheit */

2020-06-09T15:09:48Z

Fahrenheit

← Older revision		Revision as of 15:09, 9 June 2020
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	==Fahrenheit==		==Fahrenheit==

			This remains the official scale to use in just one nation - the USA.
⚫	Daniel Gabriel Fahrenheit (24 May 1686 to 16 September 1736) visited Ole Remer in 1708. In 1709 Fahrenheit originated the alcohol-in-glass thermometer, and in1724 Fahrenheit developed the scale named after him based on 3 fixed points (a slightly modified version of this scale still called Fahrenheit is still used by some people in UK and is ~~the~~ ~~official~~ scale in a ~~few~~ ~~countries~~ ~~such~~ as ~~the~~ ~~USA~~).

		⚫	Daniel Gabriel Fahrenheit (24 May 1686 to 16 September 1736) visited Ole Remer in 1708. In 1709 Fahrenheit originated the alcohol-in-glass thermometer, and in1724 Fahrenheit developed the scale named after him based on 3 fixed points (a slightly modified version of this scale still called Fahrenheit is still used by some people in UK and it is this modified scale that is the official scale in United States).

	== Rankine ==		== Rankine ==

Sfws: /* Cumulus Calculated Parameters */

2020-06-05T07:18:11Z

Cumulus Calculated Parameters

← Older revision		Revision as of 07:18, 5 June 2020
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	[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]		[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]

	[[Apparent temperature]] ~~and [[#What_formula_does_Cumulus_use_for_Apparent_Temperature.3F]]~~		[[Apparent temperature]]

			It uses a formula from the Australian BOM - http://www.bom.gov.au/info/thermal_stress/#atapproximation

			Note that the version used is the one that doesn't take into account solar radiation.

	[[Heat/cold degree days and Chill hours]]		[[Heat/cold degree days and Chill hours]]

Sfws: /* Cumulus Calculated Parameters */

2020-06-05T07:15:59Z

Cumulus Calculated Parameters

← Older revision		Revision as of 07:15, 5 June 2020
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	[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb and Dew point] and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]]		[http://en.wikipedia.org/wiki/Wet_bulb Wet bulb and Dew point] and [[#How_does_Cumulus_know_the_height_of_the_cloud_base.3F]]

	The dewpoint calculation uses a third party library which uses the Davis dewpoint calculation.		The dewpoint calculation uses a third party library which uses the Davis dewpoint calculation '''dewpoint := tempinC + ((0.13 * tempinC) + 13.6) * Ln(humidity / 100)'''

	[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]		[[Humidex]] and [[Wind chill]] and [[Heat index]] and [[#My heat index/humidex/wind chill is the same as my temperature]]