Virtual Temperature Calculator
Calculate virtual temperature for atmospheric physics and meteorology applications
Calculate Virtual Temperature
Dry bulb temperature
Water vapor mixing ratio
Temperature Difference
Air Density Effect
Formula Used
Mixing Ratio Method: Tv = T × (1 + 0.61w)
Where: T = air temperature (K), w = mixing ratio (kg/kg)
Constant: 0.61 accounts for molecular weight differences
Example Calculation
New Orleans Weather Data
Air Temperature: 91°F (32.8°C)
Dew Point: 74°F (23.3°C)
Station Pressure: 30.04 inHg (1017.27 hPa)
Application: CAPE calculation for storm prediction
Calculation Steps
1. Calculate vapor pressure: e = 6.11 × 10^(7.5 × 23.3 / (237.3 + 23.3)) ≈ 28.85 hPa
2. Apply virtual temperature formula: Tv = 306.0 / (1 - 0.379 × 28.85 / 1017.27)
3. Result: Tv ≈ 309.23 K (36.08°C or 96.95°F)
4. Temperature difference: 3.23°C (5.8°F) warmer than actual air
Application: Used for accurate CAPE calculations in severe weather forecasting
Key Concepts
Virtual Temperature
Temperature dry air would need to have the same density as moist air
Density Correction
Accounts for water vapor's lower molecular weight (18 g/mol vs 29 g/mol for dry air)
Mixing Ratio
Mass of water vapor per unit mass of dry air (g/kg or kg/kg)
Vapor Pressure
Partial pressure exerted by water vapor in the atmosphere
Moisture Levels
<0.5°C diff
Very dry air
0.5-1.5°C diff
Dry conditions
1.5-3.0°C diff
Moderate humidity
3.0-5.0°C diff
Humid conditions
>5.0°C diff
Very humid air
Applications
CAPE Calculation: Convective energy assessment
Storm Prediction: Severe weather forecasting
Hypsometric Equation: Atmospheric thickness calculations
Simplified Calculations: Use in ideal gas law for moist air
Understanding Virtual Temperature
What is Virtual Temperature?
Virtual temperature is the temperature that dry air would need to have the same density as moist air, given equal pressure and volume. This concept is crucial in atmospheric physics because water vapor has a lower molecular weight than dry air, affecting air density calculations.
Why Always Higher?
- •Molecular Weight: Water vapor (18 g/mol) vs dry air (29 g/mol)
- •Lower Density: Moist air is less dense than dry air
- •Temperature Correction: Higher virtual temperature compensates for density difference
Meteorological Applications
Virtual temperature is essential in meteorology for accurate atmospheric calculations, particularly in storm prediction and atmospheric stability analysis.
Key Applications
- •CAPE: Convective Available Potential Energy calculations
- •Storm Forecasting: Predicting thunderstorm intensity
- •Atmospheric Thickness: Hypsometric equation applications
- •Simplified Calculations: Direct use in ideal gas law
Calculation Methods and Formulas
Tv = T × (1 + 0.61w)
Mixing ratio method
Tv = T / (1 - 0.379e/p)
Dew point and pressure method
e = 6.11 × 10^(7.5Td/(237.3+Td))
Magnus formula for vapor pressure
w = 0.622 × e / (p - e)
Mixing ratio from vapor pressure
• Water vapor: 18 g/mol
• Dry air: ~29 g/mol
• Moist air is less dense
• Virtual temp > actual temp
• Difference increases with humidity
• Typical range: 0.1-10°C higher
• Accounts for buoyancy effects
• Critical for atmospheric stability
• Essential for weather prediction