1. What is Vapor Pressure Deficit?

Vapor Pressure Deficit (VPD) is the difference between the amount of moisture in the air and how much moisture the air can hold when it's saturated. It's a key parameter in agriculture, meteorology, and HVAC systems.

2. How Does the Calculator Work?

The calculator uses the VPD equation:

Where:

• \( SVP \) — Saturation vapor pressure (kPa)
• \( RH \) — Relative humidity (%)

Explanation: VPD represents the "drying power" of the air, showing how far the current conditions are from saturation.

3. Importance of VPD Calculation

Details: VPD is crucial for understanding plant transpiration rates, predicting evaporation, and designing climate control systems. It affects crop growth, building comfort, and industrial processes.

4. Using the Calculator

Tips: Enter SVP in kPa and RH as a percentage (0-100%). Both values must be valid (SVP > 0, RH between 0-100).

5. Frequently Asked Questions (FAQ)

Q1: What are typical VPD values for plants?
A: Most plants thrive at VPD between 0.8-1.2 kPa, though optimal ranges vary by species and growth stage.

Q2: How does temperature affect VPD?
A: Temperature influences SVP - warmer air can hold more moisture, increasing potential VPD at the same RH.

Q3: Why is VPD better than RH alone?
A: VPD accounts for both temperature and humidity, giving a more complete picture of atmospheric moisture conditions.

Q4: What's the relationship between VPD and evaporation?
A: Higher VPD generally means faster evaporation rates as the air can absorb more moisture.

Q5: How is VPD used in greenhouse management?
A: Growers adjust VPD to optimize plant transpiration, nutrient uptake, and prevent diseases from overly humid conditions.