Understand the mass of water vapor in unit of volume as absolute humidity, that is density of the water vapor which is contained in air. It is possible to find it through a dew point or having measured relative air humidity at present.
It is required to you
- - two identical thermometers;
- - gauze;
- - hair psychrometer;
- - psikhrometrichesky table;
- - table for definition of a dew point.
Instruction
1. Select test of air in a tight vessel and cool it. At the same time constantly control temperature. As soon as on walls of a vessel there is a dew, mark temperature at which it occurred. It will also be a dew point at which steam which is airborne becomes saturated and begins to turn into liquid. Then, by means of the special table, learn density of saturated steam at this temperature. It will also be absolute humidity of air.
2. Find absolute humidity through relative. For this purpose take two absolutely identical liquid mercury thermometers. Wind a vial of the extending liquid (mercury) of one of them with two-three layers of a gauze and moisten it with water. Wait until on thermometers temperature is established. On the damp thermometer temperature has to be lower or same, as on dry. Find the difference of their temperatures.
3. Take the psikhrometrichesky table, find in it a column of values of the dry thermometer. Find in this column value of temperature, the closest to measured. On this line carry out before crossing with a column which corresponds to the found difference of temperatures. In a cell the relative air humidity as a percentage will be specified.
4. According to the table find density of saturated steam at a temperature which is taken by the dry thermometer. Find absolute humidity, having increased relative humidity φ by density of saturated steam ρн and having divided result into 100% (ρ = φ ∙ ρн/100%).
5. Define absolute humidity more roughly, having found according to the table density of saturated steam at a temperature which is shown by the damp thermometer.
6. If there is such opportunity, determine relative humidity by means of the hair psychrometer. Then calculate absolute humidity by the technique described above. But this calculation, owing to inaccuracy of measurement of relative humidity will be the least exact.