Water Vapor in Air

Weight of water vapor in air

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Grains of moisture per pound of dry air at standard atmospheric pressure at relative humidity ranging 10 - 90% are indicated below.

Water Vapor in Air (grains^ water vapor per pound dry air*)
Relative Humidity (%)	Temperature
	(^oC)
	-1	4	10	18	22	27	32	38
	(^oF)
	30	40	50	60	70	80	90	100
10	3	4	6	8	11	16	21	29
20	5	7	10	16	21	30	42	58
30	7	11	14	22	34	46	65	87
40	9	14	20	30	44	62	85	116
50	12	18	26	39	55	78	108	147
60	14	22	32	48	66	92	128	176
70	17	26	38	54	78	108	152	208
80	19	29	42	62	88	125	173	-
90	21	33	48	70	100	140	190	-

^*grains of water is commonly used in psychrometrics

1 grain = 0.000143 lb_m = 0.0648 g (7000 grains per lb_m)

Moist air - weight of water in air - diagram

Same table as above with water vapor in "pounds water vapor per pound dry air".

Water Vapor in Air (pounds water vapor per pound dry air)
Relative Humidity (%)	Temperature
	(^oC)
	-1	4	10	18	22	27	32	38
	(^oF)
	30	40	50	60	70	80	90	100
10	0.0004	0.0006	0.0009	0.0011	0.0016	0.0023	0.0030	0.0041
20	0.0007	0.0010	0.0014	0.0023	0.0030	0.0043	0.0060	0.0083
30	0.0010	0.0016	0.0020	0.0031	0.0049	0.0066	0.0093	0.0124
40	0.0013	0.0020	0.0029	0.0043	0.0063	0.0089	0.0122	0.0166
50	0.0017	0.0026	0.0037	0.0056	0.0079	0.0112	0.0154	0.0210
60	0.0020	0.0031	0.0046	0.0069	0.0094	0.0132	0.0183	0.0252
70	0.0024	0.0037	0.0054	0.0077	0.0112	0.0154	0.0217	0.0297
80	0.0027	0.0041	0.0060	0.0089	0.0126	0.0179	0.0247	-
90	0.0030	0.0047	0.0069	0.0100	0.0143	0.0200	0.0272	-

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