Evapotranspiration Calculator
Calculate reference evapotranspiration ET₀ using the simplified Hargreaves formula from temperature and solar radiation data.
How to Use the Evapotranspiration Calculator
- Enter the maximum air temperature (°C).
- Enter the minimum air temperature (°C).
- Enter the solar radiation Ra (MJ/m²/day, default 15).
- Click Calculate to get ET₀.
Casos de Uso
- •Calculating irrigation rates using the FAO method.
- •Estimating water balance in agrometeorology.
- •Providing input data for water resource planning.
- •Agronomic calculations when weather data is limited.
Fórmula
ET₀ = 0.0023 × (T_mean + 17.8) × (T_max − T_min)^0.5 × Ra, where Ra is solar radiation (MJ/m²/day).
Preguntas Frecuentes
What is evapotranspiration?
Evapotranspiration is the combined water loss from soil evaporation and plant transpiration, expressed in mm of water per day.
How accurate is the Hargreaves method?
Hargreaves gives good results when humidity and wind data are unavailable. The Penman-Monteith method is more accurate.
What is a typical Ra value?
Ra ranges from 3-5 MJ/m²/day in winter in temperate climates to 35-40 in summer in the tropics. Default: 15 MJ/m²/day.