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CH3041
WATER
• H2O is a non-permanent
tropospheric gas
• The maximum possible vapour pressure of
water at a given temperature is called the
saturated vapour pressure p(H2O)sat.
water at a given temperature is called the
saturated vapour pressure p(H2O)sat.
• p(H2O)sat varies according
to temperature
higher T Þ higher p(H2O)sat
higher T Þ higher p(H2O)sat
eg. T = 0oC p(H2O)sat = 0.006 atm.
T = 25oC p(H2O)sat = 0.031 atm.
Relative humidity
R.H. = p(H2O)actual
/ p(H2O)sat.x 100 %
eg 80% R.H. p(H2O)actual = 0.0048 atm at 0oC
= 0.025 atm. at 25oC
