Vapour-pressure deficit the plant may dry out and die. For this reason the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 and 0.95 kPa. In ecology, it is the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. Unlike relative humidity, vapour-pressure deficit has a simple nearly straight-line relationship to the rate of evapotranspiration and other measures of evaporation. To compute the VPD, we need the ambient (greenhouse) air
What Is... Cliff Clavin? book "Brainiac", noted that "Jeopardy!"-related sitcom episodes had become common at the time. On the first episode of "Jeopardy!" season 31, which aired on September 15, 2014, "Jeopardy!" champion Elizabeth Williams echoed Cliff Clavin's answer in her response to the Final Jeopardy clue. Williams's $600 wager combined with her opponents' incorrect responses allowed Williams to triumph that day, nonetheless. The episode inspired the term "Clavin's Rule" in reference to maximizing all the winnings at the final round and losing them all. What Is... Cliff Clavin? "What Is... Cliff Clavin?" is an eighth season episode of the American television series "Cheers".