Our powerful absolute humidity calculator is used to measure the amount of water vapor present in a given volume of air using AH = m / V formula.
With a room with a volume of 100 cubic meters, the absolute humidity calculator will determine that there are 2 kilograms of water vapor in this space, the absolute humidity would be 0.02 kg/m³.
Absolute Humidity Calculator
| Temperature (°C) | Relative Humidity (%) | Absolute Humidity (kg/m³) |
|---|---|---|
| 0 | 100 | 0.0006 |
| 5 | 90 | 0.0042 |
| 10 | 80 | 0.0094 |
| 15 | 40 | 0.0051 |
| 15 | 60 | 0.0077 |
| 20 | 50 | 0.0086 |
| 20 | 70 | 0.0121 |
| 25 | 60 | 0.0138 |
| 25 | 80 | 0.0183 |
| 30 | 70 | 0.0210 |
| 30 | 90 | 0.0272 |
| 35 | 80 | 0.0336 |
| 35 | 90 | 0.0404 |
| 40 | 50 | 0.0191 |
| 40 | 70 | 0.0271 |
Absolute Humidity Formula
The formula for calculating absolute humidity is:
AH = m / VWhere:
- AH is the absolute humidity (typically in kg/m³)
- m is the mass of water vapor (in kg)
- V is the volume of air (in m³)
If we have 0.5 kg of water vapor in a 50 m³ space, the calculation would be:
AH = 0.5 kg / 50 m³ = 0.01 kg/m³How to Calculate Absolute Humidity?
To calculate absolute humidity, follow these simple steps:
- Measure the mass of water vapor in a given space.
- Determine the volume of the air in question.
- Divide the mass by the volume.
A greenhouse contains 3 kg of water vapor in a 200 m³ area.
Calculation: AH = 3 kg / 200 m³ = 0.015 kg/m³
How to Convert Absolute Humidity to Specific Humidity?
To convert absolute humidity to specific humidity:
Calculate the density of dry air at the given temperature and pressure.
Add the absolute humidity to the dry air density to get the total air density.
Divide the absolute humidity by the total air density.
Specific humidity is the ratio of water vapor mass to the total mass of moist air.
- Absolute humidity: 0.010 kg/m³
- Dry air density at 25°C and 1 atm: 1.184 kg/m³
- Total air density: 1.184 + 0.010 = 1.194 kg/m³
- Specific humidity: 0.010 / 1.194 = 0.00838 kg/kg or 8.38 g/kg
What is the Absolute Humidity Value?
The absolute humidity value is the mass of water vapor per unit volume of air, typically expressed in kg/m³ or g/m³. This value can range from near 0 in extremely dry conditions to around 0.030 kg/m³ in very humid, tropical environments.
For instance, a comfortable indoor environment might have an absolute humidity of 0.008 to 0.012 kg/m³.
What is g/kg in Humidity?
The unit g/kg in humidity refers to grams of water vapor per kilogram of dry air, which is a measure of specific humidity. This unit is often used in meteorology and air conditioning calculations.
If the specific humidity is 10 g/kg, it means there are 10 grams of water vapor for every kilogram of dry air in the mixture.
What is the Relationship Between Absolute Humidity and Temperature?
Temperature and absolute humidity have a direct relationship. As temperature increases, the air’s capacity to hold water vapor also increases. This relationship is not linear but follows the Clausius-Clapeyron equation.
For example:
- At 0°C, air can hold up to about 0.005 kg/m³ of water vapor.
- At 20°C, this increases to about 0.017 kg/m³.
- At 30°C, it can hold up to 0.030 kg/m³.
What is the Absolute Humidity at 25°C?
At 100% relative humidity (saturation point), the maximum absolute humidity at 25°C is approximately 0.023 kg/m³.
Calculations:
- At 50% relative humidity: 0.023 × 0.5 = 0.0115 kg/m³
- At 75% relative humidity: 0.023 × 0.75 = 0.01725 kg/m³
Is 65 Percent Humidity High?
Generally, for indoor environments:
- At lower temperatures (18-22°C), 65% humidity might feel comfortable.
- At higher temperatures (25-30°C), 65% humidity could feel uncomfortably muggy.
For outdoor conditions, 65% is moderate to high, potentially leading to increased perspiration and discomfort, especially in warmer weather.
Is 70 Percent Humidity High?
A relative humidity of 70% is generally considered very high, especially in warmer temperatures. At this level:
- Indoor environments may feel stuffy and promote mold growth.
- Outdoor activities can become uncomfortable due to reduced evaporative cooling.
- In colder temperatures, it might lead to increased perception of chill due to higher heat conductivity of moist air.
References
- American Meteorological Society – Glossary of Meteorology
- Engineering ToolBox – Moisture in Air
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