Pan evaporation

Pan evaporation is a measurement that combines or integrates the effects of several climate elements: temperature, humidity, rain fall, drought dispersion, solar radiation, and wind.

Evaporation is greatest on hot, windy, dry, sunny days; and is greatly reduced when clouds block the sun and when air is cool, calm, and humid.

[1] Pan evaporation measurements enable farmers and ranchers to understand how much water their crops will need.

Often the evaporation pans are automated with water level sensors and a small weather station is located nearby.

[5] Also, research has been done about the installation practices of evaporation pans so that they can make more reliable and repeatable measurements.

The pan rests on a carefully leveled, wooden base and is often enclosed by a chain link fence to prevent animals drinking from it.

The Class A Evaporation Pan is of limited use on days with rainfall events of >30mm (203mm rain gauge) unless it is emptied more than once per 24hours.

The most common and obvious error is in daily rainfall events of >55mm (203mm rain gauge) where the Class A Evaporation pan will likely overflow.

[10][11][12][13] It is currently theorized that, all other things being equal, as the global climate warms evaporation would increase proportionately and as a result, the hydrological cycle in its most general sense is bound to accelerate.

[citation needed] "It is generally agreed that the evaporation from pans has been decreasing for the past half century over many regions of the Earth.

However, the significance of this negative trend, as regards terrestrial evaporation, is still somewhat controversial, and its implications for the global hydrologic cycle remain unclear.