Evapotranspiration Matrix

Input Parameters

Air Temperature (°C) Relative Humidity (%) Wind Speed (m/s) @ 2m Solar Radiation (MJ/m²/day) Crop Coefficient (Kc)

Reference ET₀ (mm/day) --.--

Crop ETc (mm/day) --.--

Water Demand (L/m²/day) --.--

Vapor Pressure Deficit (kPa) --.--

Status: AWAITING INPUT

Parameter	Symbol	Units	Source
Slope Vapor Pressure Curve	Δ	kPa °C⁻¹	Tetens Eq.
Psychrometric Constant	γ	kPa °C⁻¹	Standard Atmosphere
Net Radiation	Rₙ	MJ m⁻² day⁻¹	Allen et al. (1998)
Soil Heat Flux	G	MJ m⁻² day⁻¹	Daily Avg ≈ 0

Grounded In: FAO Irrigation and Drainage Paper 56.
Calibrated For: Utah Valley Microclimates (40°N, 111°W).

This tool calculates potential evapotranspiration using the standardized Penman-Monteith equation. It does not predict poetry. It predicts thirst.