Table 2 Precipitable Water Vapour Depth (In Metres)
Altitude
|
Latitude
|
(air pressure)
|
0
|
30
|
45
|
60
|
70
|
Warm or wet season
|
1000 mb mean
|
0.05
|
0.04
|
0.025
|
0.02
|
0.018
|
min.
|
0.02
|
0.02
|
0.01
|
0.007
|
0.007
|
max.
|
0.1
|
0.07
|
0.04
|
0.04
|
0.04
|
|
|
|
|
|
|
900 mb mean
|
0.03
|
0.019
|
0.016
|
0.0125
|
0.011
|
min.
|
0.01
|
0.007
|
0.007
|
0.004
|
0.004
|
max.
|
0.07
|
0.04
|
0.04
|
0.02
|
0.02
|
|
|
|
|
|
|
800 mb mean
|
0.02
|
0.015
|
0.01
|
0.008
|
0.007
|
min.
|
0.01
|
0.007
|
0.004
|
0.004
|
0.002
|
max.
|
0.04
|
0.04
|
0.02
|
0.02
|
0.02
|
|
|
|
|
|
|
700 mb mean
|
0.01
|
0.008
|
0.005
|
0.004
|
0.0035
|
min.
|
0.004
|
0.004
|
0.002
|
0.002
|
0.001
|
max.
|
0.02
|
0.02
|
0.01
|
0.01
|
0.01
|
|
|
|
|
|
|
Cold or dry season
|
1000 mb mean
|
0.03
|
0.015
|
0.008
|
0.005
|
0.003
|
min.
|
0.01
|
0.004
|
0.004
|
0.002
|
0.001
|
max.
|
0.07
|
0.04
|
0.02
|
0.01
|
0.01
|
|
|
|
|
|
|
900 mb mean
|
0.02
|
0.01
|
0.005
|
0.0035
|
0.002
|
min.
|
0.007
|
0.004
|
0.002
|
0.002
|
0.001
|
max.
|
0.04
|
0.02
|
0.01
|
0.01
|
0.007
|
|
|
|
|
|
|
800 mb mean
|
0.01
|
0.006
|
0.003
|
0.002
|
0.001
|
min.
|
0.004
|
0.002
|
0.001
|
0.001
|
0.0005
|
max.
|
0.02
|
0.02
|
0.01
|
0.007
|
0.002
|
|
|
|
|
|
|
700 mb mean
|
0.006
|
0.003
|
0.0015
|
0.001
|
0.0005
|
min.
|
0.002
|
0.001
|
0.001
|
0.0005
|
0.0002
|
max.
|
0.01
|
0.01
|
0.004
|
0.002
|
0.001
|
From 'Solar Radiation', ed. by N. Robinson. Maps from Engineering Data Unit.