Dew Point Definition | What is Dew Point?
Dew Point in Simple Terms is nothing but the temperature at which water vapor begins to condense into water. For Example: If you have a high relative humidity in your room you will see dew forming on the window surface. It is because the surroundings of the window has dropepd below the dew point.
What is Relative Humidity?
Relative Humidity is nothing but the ratio of current absolute humidity to the maximum absolute humidity for that particular temperature. In other words, we can say that the amount of mositure in the air compared to the maximum amount of air that the temperature can hold.
relative_humidity = 100% * current absolute humidity / max absolute humidity at current temperature
The Relative Humidity put in other words is the ratio of water vapor pressure Pw to Saturation Water Vapor Pressure Pws i.e. relative_humidity = 100% * Pw / Pws
To understand the relative humidity you need to know about absolute humidity at first. Absolute Humidity is nothing but the water content in air and is expressed in units grams per cubic meter. Formula for absolute humidity is absolute humidity = m / V where m is the mass of water vapor, V is the Volume of Air and Water Vapor Mixture.
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How to Calculate Dew Point?
There are many equations that describe the relationship between dew point and relative humidity. Among all those we have compiled a Magnus-Tetens Formula that provides you with the accurate results for temperatures ranging between -45°C to 60°C. Dew Point Formula is given by Ts = (bα(T,RH)) / (a - α(T,RH))
- Where, Ts is the Dew point
- T is the Temperature
- RH is the relative humidity of air
- a, b are coefficients, and for Sonntag90 constant set, a = 17.62 and b = 243.12°C
- α(T,RH) = ln(RH/100) + aT/(b+T)
Dew Point Vs Humidity
Dew Point & Relative Humidity are closely related and it is difficult to understand the difference. Now that we have explained the formulas of dew point, relative humidity let us dive into the concept much better. Dew Point is the accurate measurement of moisture in air. The higher the dew point is the more mositure content exists in the air. Relative Humidity on the other hand is a value that depends both on temperature and pressure.
The greater the relative humidity is the closer the dew point is to the current air temperature. In a particular case when the air is satured maximum with water the dew point is equal to current temperature.
What is Comfortable Dew Point?
High Dew Point can result in discomfort. Usually, in high termperatures our bodies take more time for evaporation of sweat as the air is already saturated with water.
|Dew point||Comfort levels|
|<50°F (<10°C)||a bit dry for some|
|50 - 60°F
(10 - 16°C)
|dry and comfortable|
|60 - 65°F
(16 - 18°C)
|65 - 70°F
(18 - 21°C)
|unpleasant, lots of moisture in the air|
|uncomfortable, oppressive, even dangerous above 75°F|
Applications of Dew Point
There are several applications for dew point and they are listed as follows
- Meteorology - It is used to express the amount of mositure in air.
- Aviation - In Aviation Industry Dew Point Temperature is found to evaluate the probability of a carburetor icing, or fog appearing.
- Technology - Dew Point Meters are used in electronics, optics and for generation of various technical gases like H2, N2, O2, Ar, etc.
- Agriculture - In Order to sustain optimal humidity in greenhouse and avoid water condensation on plants dew point is used.
- Medicine - It is used for monitoring the sterilization process.
Frequently Asked Questions on Dew Point Calculator
1. What is Dew Point in Simple Terms?
Dew Point is the highest possible temperature at which water vapor can condense and form dew.
2. What is Dew Point Formula?
Dew Point Formula is given by the expression Ts = (bα(T,RH)) / (a - α(T,RH))
3. What happens if dew point is higher than temperature?
The higher the dew point rises, the greater the amount of moisture in air leading to discomfort.