1. What is Saturation Vapour Pressure?

Saturation vapour pressure (e_s) is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature. It represents the maximum amount of water vapor the air can hold at a specific temperature.

2. How Does the Magnus Formula Work?

The calculator uses the Magnus formula:

Where:

• \( e_s \) — Saturation vapour pressure (hPa)
• \( T \) — Temperature (°C)
• \( \exp \) — Exponential function

Explanation: The Magnus formula provides an empirical relationship between temperature and saturation vapour pressure, widely used in meteorology and atmospheric sciences.

3. Importance of Saturation Vapour Pressure Calculation

Details: Accurate calculation of saturation vapour pressure is essential for weather forecasting, humidity measurement, climate studies, and various industrial processes involving air-water vapor systems.

4. Using the Calculator

Tips: Enter temperature in degrees Celsius. The calculator will compute the saturation vapour pressure in hectopascals (hPa) using the Magnus formula.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of validity for the Magnus formula?
A: The Magnus formula is generally valid for temperatures between -45°C and +60°C, though accuracy may vary at extreme temperatures.

Q2: How does saturation vapour pressure relate to relative humidity?
A: Relative humidity = (actual vapour pressure / saturation vapour pressure) × 100%. It indicates how close the air is to being saturated.

Q3: Why does saturation vapour pressure increase with temperature?
A: Warmer air can hold more water vapor molecules because increased thermal energy allows more water molecules to escape from liquid to vapor phase.

Q4: Are there alternative formulas for calculating saturation vapour pressure?
A: Yes, other formulas include the Goff-Gratch equation, Buck equation, and Tetens formula, each with different coefficients and ranges of applicability.

Q5: What are typical values of saturation vapour pressure?
A: At 0°C: ~6.11 hPa, at 20°C: ~23.39 hPa, at 40°C: ~73.78 hPa. The value approximately doubles for every 10°C temperature increase.