Problem

If the air temperature is 35°C and the dew point is 21°C, determine the relative humidity...

If the air temperature is 35°C and the dew point is 21°C, determine the relative humidity using

(a) Table, p. 107;

(b) Fig., p. 99

Table Saturation Vapor Pressure over Water for Various Air Temperatures*

AIR TEMPERATURE		SATURATION VAPOR PRESSURE	AIR TEMPERATURE		SATURATION VAPOR PRESSURE
(°C)	(°F)	(MB)	(°C)	(°F)	(MB)
–18	(0)	1.5	18	(65)	21.0
–15	(5)	1.9	21	(70)	25.0
–12	(10)	2.4	24	(75)	29.6
–9	(15)	3.0	27	(80)	35.0
–7	(20)	3.7	29	(85)	41.0
–4	(25)	4.6	32	(90)	48.1
–1	(30)	5.6	35	(95)	56.2
2	(35)	6.9	38	(100)	65.6
4	(40)	8.4	41	(105)	76.2
7	(45)	10.2	43	(110)	87.8
10	(50)	12.3	46	(115)	101.4
13	(55)	14.8	49	(120)	116.8
16	(60)	17.7	52	(125)	134.2

FIGURE Saturation vapor pressure increases with increasing temperature. At a temperature of 10°C, the saturation vapor pressure is about 12 mb, whereas at 30°C it is about 42 mb. The inset illustrates that the saturation vapor pressure over water is greater than the saturation vapor pressure over ice.