How does water pressure change with increasing temperature? With air inside, assuming for simplicity constant volume and ideal gas, its pressure variation from 50F to 212F can be computed from T in K: P2/P1 = T2/T1 = 373.15/283.15 = 1.32. Adding the vapour pressure, at 100C the pressure inside is 1.37 + 1.00 = 2.37 atm. This doesn't consider however the volume variation. Since some liquid water becomes vapour, the volume available for the gases increases and this reduces the air pressure, so the final result would be less than 2.37 atm.
Usually planted in the early fall, cool-season grass seeds prefer daytime temperatures ranging from 60 to 75 F. With this temperature range, the soil itself is usually between 50 and 65 F -- the right environment for germination.ermination Failure. Grass seeds may fail if the temperatures aren't right for the particular type of grass. For example, warm-season grasses planted during a spring cold snap will stay dormant. As they lay in the soil, surrounding weed seeds take over the space and make it harder for the grass to become established.
The germination time for grass seed ranges from 5 to 30 days depending on the variety. It can be even longer than this in cooler temperatures. This is how long it will take to actually see the grass growing. Until this point, the seed, or the soil and mulch in contact with the seed, must stay moist.It doesnât need to be soggy or swimming, but moist. Once the new grass is visible, the roots are also growing down into the soil. Avoid the hottest season or occasional heat-spells when planting. 2  Watering new grass seed is enough of a challenge without taking on the heat as an enemy. 3  If you have no choice, be vigilant and accept the need to apply water more frequently as it dries out more quickly.