3. Order of the work

1. Moisten the gauze of wet thermometer.

2. Set a spring of ventilator with the help of handle.

3. Wait until fixation of the wet thermometer index.

4. Write down the indexes of wet and dry thermometer t_wet and t_dry into table 1 and define relative humidity with the help of psychrometric table 3.

Table 1. Measurement and calculation results

№	tdry, OC	Twet, OC	Difference of thermometer indexes ,°С	ρs, g m-3	ps, mm Hg	Relative air humidity В, %	Absolute air humidity а, g m-3	Dew point td , °С
Average value
Error

5. On the base of the formula of relative humidity definition and with the help of table 2 find the absolute humidity of the air. Put in the values of saturated water vapor density and pressure in the room into table 1.

Table 2. Pressure and density of saturated water vapor

t,0С			t,0С
	4,6	4,8		13,63	13,6
	4,9	5,2		14,53	14,5
	5,3	5,60		15,48	15,4
	5,7	6,0		16,48	16,3
	6,1	6,40		17,54	17,3
	6,6	6,8		18,65	18,3
	7,0	7,30		19,83	19,4
	7,6	7,80		21,07	20,6
	8,0	8,30		22,38	21,8
	8,6	8,80		23,76	23,0
	9,2	9,40		25,21	24,4
	9,8	10,0		26,74	25,8
	10,5	10,7		28,35	27,2
	11,2	11,4		30,04	28,7
	12,0	12,1		31,82	30,3
	12,8	12,8

6. Repeat 1-5 items 3-4 times.

7. Calculate the average values of absolute and relative humidity Bav, ρav and relative errors.

8. Define the dew point with the use of table 4.

9. Make up conclusions:

• how much water does 1 m³ of the air contain?

• is the humidity normal, high or low?