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 an important metric in agriculture, horticulture, and climate control.

2. How Does the Calculator Work?

The calculator uses the VPD equation:

Where:

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

Explanation: VPD measures the "dryness" of air by comparing how much water vapor is in the air versus how much it could hold at saturation.

3. Importance of VPD Calculation

Details: VPD is crucial for understanding plant transpiration rates, managing greenhouse environments, and optimizing growing conditions for crops.

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: Warmer air can hold more moisture, so SVP increases with temperature, affecting VPD calculations.

Q3: Why is VPD important in agriculture?
A: VPD directly affects plant transpiration rates, nutrient uptake, and overall plant health.

Q4: What's the relationship between VPD and RH?
A: RH measures current moisture relative to maximum at a given temperature, while VPD measures the "drying potential" of the air.

Q5: Can VPD be too high or too low?
A: Yes, both extremes can stress plants - too high causes excessive water loss, too low can limit transpiration and nutrient flow.