Updated by Travis Bates

ZENTRA Cloud follows the standard FAO 56 Penman-Monteith guidelines for calculating evapotranspiration. Users can choose between ETr (alfalfa) reference or ETo (grass) reference depending on preference.

Standardized Reference Evapotranspiration Equation:

METER Sensors that support ET:

OR a combination of


  • Click the environmental model icon.
  • Select ETo or ETr.
  • Enter a name for the model and a name for the chart.
  • The default wind measurement height is 2 meters. Enter a custom value if needed.
  • Select a device. The sensor inputs for Wind Speed, Solar Radiation, Vapor Pressure and Air Temperature will auto-populate. Select different sources for these inputs if necessary.
  • Click Create.

Accumulated ETo

  • Click the Vertical Ellipse icon.
  • Select Stats.
  • Toggle the desired measurements.
  • Click Accept.

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