1. What is Change in Vapour Pressure?

Change in Vapour Pressure refers to the difference between maximum vapour pressure and actual vapour pressure. It is an important parameter in evaporation studies and hydrological calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \delta V \) — Change in Vapour Pressure (cmHg)
• \( E_m \) — Evaporation Loss per Month (m)
• \( C \) — Meyer's Constant (1.1 for deep water, 1.5 for shallow water)
• \( u \) — Mean Wind Velocity (cm/s)

Explanation: This formula calculates the change in vapour pressure based on evaporation loss, Meyer's constant, and wind velocity using Meyer's evaporation formula.

3. Importance of Vapour Pressure Calculation

Details: Accurate vapour pressure calculation is crucial for evaporation studies, hydrological modeling, water resource management, and climate studies.

4. Using the Calculator

Tips: Enter evaporation loss in meters, Meyer's constant (typically 1.1 or 1.5), and mean wind velocity in cm/s. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is Meyer's Constant?
A: Meyer's Constant is an empirical coefficient in the Meyer evaporation formula, typically 1.1 for deep water and 1.5 for shallow water.

Q2: How is wind velocity measured?
A: Mean Wind Velocity refers to wind measured in centimeters per second at a height of about 9 meters above the ground.

Q3: What units are used for evaporation loss?
A: Evaporation Loss per Month is measured in meters, representing the amount of water evaporated over a monthly period.

Q4: What are typical values for change in vapour pressure?
A: Values vary depending on climatic conditions, but typically range from 0.01 to 0.1 cmHg in most environments.

Q5: When is this calculation most useful?
A: This calculation is particularly useful in hydrology, irrigation planning, reservoir management, and climate change studies.