METEOROLOGY – HUMIDITY & WATER VAPOUR CALCULATOR
Evapotranspiration Fao56
A precise tool.
What is the Evapotranspiration Fao56 & How does it work?
Evapotranspiration (ETβ) is a measure of the amount of water that is transferred from the land surface to the atmosphere through evaporation and plant transpiration. The FAO-56 Penman-Monteith method provides a comprehensive approach to estimating ETβ, taking into account various meteorological factors such as temperature, humidity, wind speed, solar radiation, and net radiation.The FAO-56 Penman-Monteith method is widely used in agriculture and water management to estimate the water requirements of crops. It provides a more accurate estimation compared to simpler methods by considering the effects of wind speed and humidity on evaporation.
ETβ = frac{0.408 Delta (R_n – G) + gamma frac{900}{T + 273} u_2 e_a}{Delta + gamma (1 + 0.34 u_2)}
ETβ = Reference evapotranspiration, mm/day
Ξ = Slope of the saturation vapor pressure curve at air temperature, kPa/Β°C
R_n = Net radiation at the crop surface, MJ/mΒ²/day
G = Soil heat flux density, MJ/mΒ²/day
Ξ³ = Psychrometric constant, kPa/Β°C
T = Mean air temperature at 2 m height, Β°C
u_2 = Wind speed at 2 m height, m/s
e_a = Actual vapor pressure, kPa
Ξ = Slope of the saturation vapor pressure curve at air temperature, kPa/Β°C
R_n = Net radiation at the crop surface, MJ/mΒ²/day
G = Soil heat flux density, MJ/mΒ²/day
Ξ³ = Psychrometric constant, kPa/Β°C
T = Mean air temperature at 2 m height, Β°C
u_2 = Wind speed at 2 m height, m/s
e_a = Actual vapor pressure, kPa
Parameters
Result
β
Frequently Asked Questions
What is evapotranspiration?
Evapotranspiration (ETβ) is the amount of water that evaporates from the land surface and transpires through plants into the atmosphere.
How does the FAO-56 method calculate ETβ?
The FAO-56 Penman-Monteith method calculates ETβ by considering temperature, humidity, wind speed, solar radiation, and net radiation to provide a comprehensive estimate of water loss from the land.
What are the key inputs for this calculator?
The key inputs include air temperature, relative humidity, wind speed at 2 meters, solar radiation, and net radiation.
Why is the FAO-56 method used for ETβ calculation?
The FAO-56 method is widely used because it provides a detailed and accurate estimation of evapotranspiration, considering various environmental factors.
What units should I use for the inputs?
Use Celsius for temperature, percentage for relative humidity, meters per second for wind speed, megajoules per square meter for solar radiation, and watts per square meter for net radiation.
How do I interpret the result of ETβ?
The result represents the amount of water evaporated from the land surface and transpired by plants in millimeters per day.
Can this calculator be used for any location?
Yes, but ensure that the input data accurately reflects the local conditions to get a reliable ETβ estimate.
Results are for informational purposes only and do not constitute professional advice.