Precipitable water column

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The precipitable water column (in millimeters or inches) is the amount of water in the whole atmospheric column. It represents the height that would reach the total amount of the water in liquid state over a surface of 1 square meter.

[edit] Measurement

There are different techniques:

- A type of measurement is based on the measurement of the solar irradiance on two wavelengths: one of them is in a water absorption band, and the other is not. The precipitable water column is determined using the irradiances in these bands and the Beer-Lambert law.

- The precipitable water can also be calculated by integration of radiosonde data (relative humidity, pressure and temperature) over the whole atmosphere.

- Recently it has been proposed a measurement technique from the satellite sensor GOME onboard on the ERS-2 satellite

[edit] External links

• Microtops II An instrument to measure the precipitable water column on the ground level.

• GRL Precipitable water measurement from satellite published in Geophysical Research Letters.