![]() As a result, the electronics of the evaluation unit do not have to be protected separately and the device is more easily accessible for the user. For use at particularly high or low temperatures, humidity and temperature loggers are usually equipped with external sensors. Humidity and temperature loggers for stationary use are often permanently installed and supplied via mains voltage. Power is often supplied by a battery that can be recharged via a Mini-USB interface. Mobile versions without a display that cannot show any values are usually very small and can record data at the measuring point over many days. There are many different types of humidity and temperature loggers. Types of humidity and temperature data loggers for mobile or stationary use in relation to the maximum humidity content at the current temperature. It is customary to specify the humidity as relative humidity, i.e. Humidity and temperature loggers measure values for temperature and humidity at fixed time intervals and saves them or forwards them directly to external storage. An electronic device called a logger records the respective measured variables with the integrated or connected sensors at regular intervals and saves them for later evaluation. And now a paradoxical question: which of those two situations would feel more humid? Definitely the second one! The dew point is the value we should look at if we want to know how dry or humid it is outside, not the relative humidity.The term “log” stands for logging or recording.The dew point is 60 ☏ (~15.5 ☌), so following the formula, we can find out that the relative humidity is ~60%. Let's take another example: summer finally has come, we are relaxing near a river, and the temperature is 75 ☏ (24 ☌).Our forecast shows that the dew point is equal to 40 ☏ as well – so the relative humidity is 100%. ![]() ![]() Imagine that it's a cold autumn morning, 40 ☏ outside (~4.5 ☌).To better understand the difference between dew point and humidity, let's look at this example: In a particular case, when the air is maximally saturated with water (the relative humidity is 100%), the dew point is equal to the current temperature. Relative humidity is a more confusing value as it depends on temperature and the pressure of the system in question.ĭew point and relative humidity are not the same, but they are closely related: the higher relative humidity is, the closer the dew point is to the current air temperature. If you want to know whether (or weather, heh) it's comfortable or not to have a morning jog or go on a weekend hiking trip – stick with that term. The higher the dew point is, the more moisture that is in the air. Now that you know the formulas for dew point and humidity, you may wonder, what is the difference between those two terms?ĭew point is an accurate measurement of the moisture content in the air. Or, simply type the values into our dew point calculator (you can also use the relative humidity calculator). If you want to calculate relative humidity, you need to know the dew point and temperature to use the equation derived from the above formula. As recommended by Alduchov and Eskridge, the value of these are: a = 17.625 and b = 243.04 ☌ and RH - Relative humidity of the air (in percent).The dew point is calculated according to the following formula: Lawrence from 2005) that allows us to obtain accurate results (with an uncertainty of 0.35 ☌) for temperatures ranging from -45 ☌ to 60 ☌. This dew point calculator uses the Magnus-Tetens formula ( based on the article by Mark G. Many equations describing this relationship have been formed. It is merely the water content in the air, expressed in grams per cubic meter:Ībsolute humidity = m / V, where m is the mass of water vapor, and V is the volume of the air and water vapor mixture.įor saturated air at 30 ☌ (86 ☏), the absolute humidity in the atmosphere ranges from ~0 to 30 grams per cubic meter.ĭid you notice that the formulas don't take the temperature into consideration? To understand this definition, you also need to know the meaning of absolute humidity. Or, expressed differently, the relative humidity is the ratio of the water vapor pressure Pw to the saturation water vapor pressure Pws at the given temperature: Relative humidity = 100% × current absolute humidity / max absolute humidity In other words, it's the amount of moisture in the air compared to what the air can maximally "hold" at that temperature: It is the ratio of the current absolute humidity to the maximum absolute humidity possible for the current temperature. Relative humidity is expressed as a percentage.
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