Tip: click anywhere on the chart to jump the sliders to that point. Link the air/leaf sliders to move them together at a fixed offset (useful for modeling a constant leaf-to-air temperature gap).
Vapor pressure deficit (VPD) is the gap between how much moisture the air could hold if fully saturated and
how much it actually holds. A higher VPD pulls moisture out of leaves faster (stronger transpiration); a lower
VPD slows it down. Because both air temperature and leaf temperature affect the saturation point, growers track
both, not just relative humidity. This tool uses the standard Tetens approximation for saturation vapor pressure.