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 It Is to Burn album turned out to be a bit of a disappoinment due to the large amount of hype surrounding the release, giving it an overall 3 stars. "What It Is to Burn" charted at number 99 on the "Billboard" 200 and number 1 on the Heatseekers Albums charts. It also charted at number 177 in the UK. "Letters to You" charted in the UK at number 39. "What It Is to Burn" charted at number 15 on the Alternative Songs chart and number 35 on the Mainstream Rock chart. By April 2003, the album had sold over 200,000 copies in the