FormulaDen.com

Physics Chemistry Math Chemical Engineering Civil Electrical Electronics Electronics and Instrumentation Materials Science Mechanical Production Engineering Financial Health

Penman's Equation Formula

Fx Copy

LaTeX Copy

Daily Potential Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. Check FAQs

PET = \frac{A \cdot H n + E a \cdot γ}{A + γ}

PET - Daily Potential Evapotranspiration?A - Slope of Saturation Vapour Pressure?H_n - Net Radiation of Evaporable Water?E_a - Parameter of Wind Velocity and Saturation Deficit?γ - Psychrometric Constant?

Penman's Equation Example

With values

With units

Only example

Here is how the Penman's Equation equation looks like with Values.

Here is how the Penman's Equation equation looks like with Units.

Here is how the Penman's Equation equation looks like.

2.0594 = \frac{1.05 \cdot 1.99 + 2.208 \cdot 0.49}{1.05 + 0.49}

2.0594 = \frac{1.05 \cdot 1.99 + 2.208 \cdot 0.49}{1.05 + 0.49}

2.0594 = \frac{1.05 \cdot 1.99 + 2.208 \cdot 0.49}{1.05 + 0.49}

Tip: Use pencil ( Pencil

) icon above to edit Input Values and Units.

Calculate

Recalculate

Solution

Copy

Reset

You are here -

Home » Category

Engineering » Category

Civil » Category

Engineering Hydrology » fx Penman's Equation

Penman's Equation Solution

Follow our step by step solution on how to calculate Penman's Equation?

FIRST Step Consider the formula

PET = \frac{A \cdot H n + E a \cdot γ}{A + γ}

Next Step Substitute values of Variables

∴

PET = \frac{1.05 \cdot 1.99 + 2.208 \cdot 0.49}{1.05 + 0.49}

Next Step Prepare to Evaluate

∴

PET = \frac{1.05 \cdot 1.99 + 2.208 \cdot 0.49}{1.05 + 0.49}

Next Step Evaluate

∴

PET = 2.05936363636364

LAST Step Rounding Answer

∴

PET = 2.0594

Penman's Equation Formula Elements

Variables

Daily Potential Evapotranspiration

Daily Potential Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.

Symbol: PET

Measurement: NAUnit: Unitless

Note: Value should be greater than 0.

Formulas to find Daily Potential Evapotranspiration

Slope of Saturation Vapour Pressure

Slope of Saturation Vapour Pressure vs temperature curve at the mean air temperature, in mm of mercury per °C.

Symbol: A

Measurement: NAUnit: Unitless

Note: Value should be greater than 0.

Formulas to find Slope of Saturation Vapour Pressure

Net Radiation of Evaporable Water

Net Radiation of Evaporable Water length per day influenced by the incoming solar radiation absorbed by the Earth's surface and the radiation reflected back.

Symbol: H_n

Measurement: NAUnit: Unitless

Note: Value should be greater than 0.

Formulas to find Net Radiation of Evaporable Water

Parameter of Wind Velocity and Saturation Deficit

Parameter of Wind Velocity and Saturation Deficit.

Symbol: E_a

Measurement: NAUnit: Unitless

Note: Value should be greater than 0.

Formulas to find Parameter of Wind Velocity and Saturation Deficit

Psychrometric Constant

Psychrometric Constant relates the partial pressure of water in air to the air temperature.

Symbol: γ

Measurement: NAUnit: Unitless

Note: Value should be greater than 0.

Formulas to find Psychrometric Constant

Other formulas in Evapotranspiration Equations category

Go Equation for Blaney Criddle

E T = 2.54 \cdot K \cdot F

Go Thornthwaite Formula

E T = 1.6 \cdot L a \cdot {(\frac{10 \cdot T a}{I t})}^{a Th}

Go Adjustment related to Latitude of Place given Potential Evapotranspiration

L a = \frac{E T}{1.6 \cdot {(\frac{10 \cdot T a}{I t})}^{a Th}}

Go Mean Monthly Air Temperature for Potential Evapotranspiration in Thornthwaite Equation

T a = {(\frac{E T}{1.6 \cdot L a})}^{\frac{1}{a Th}} \cdot (\frac{I t}{10})

How to Evaluate Penman's Equation?

Penman's Equation evaluator uses Daily Potential Evapotranspiration = (Slope of Saturation Vapour Pressure*Net Radiation of Evaporable Water+Parameter of Wind Velocity and Saturation Deficit*Psychrometric Constant)/(Slope of Saturation Vapour Pressure+Psychrometric Constant) to evaluate the Daily Potential Evapotranspiration, The Penman's Equation formula is defined as the evaporation (E) from an open water surface and was developed by Howard Penman in 1948. Daily Potential Evapotranspiration is denoted by PET symbol.

How to evaluate Penman's Equation using this online evaluator? To use this online evaluator for Penman's Equation, enter Slope of Saturation Vapour Pressure (A), Net Radiation of Evaporable Water (H_n), Parameter of Wind Velocity and Saturation Deficit (E_a) & Psychrometric Constant (γ) and hit the calculate button.

FAQs on Penman's Equation

What is the formula to find Penman's Equation?

The formula of Penman's Equation is expressed as Daily Potential Evapotranspiration = (Slope of Saturation Vapour Pressure*Net Radiation of Evaporable Water+Parameter of Wind Velocity and Saturation Deficit*Psychrometric Constant)/(Slope of Saturation Vapour Pressure+Psychrometric Constant). Here is an example- 2.059364 = (1.05*1.99+2.208*0.49)/(1.05+0.49).

How to calculate Penman's Equation?

With Slope of Saturation Vapour Pressure (A), Net Radiation of Evaporable Water (H_n), Parameter of Wind Velocity and Saturation Deficit (E_a) & Psychrometric Constant (γ) we can find Penman's Equation using the formula - Daily Potential Evapotranspiration = (Slope of Saturation Vapour Pressure*Net Radiation of Evaporable Water+Parameter of Wind Velocity and Saturation Deficit*Psychrometric Constant)/(Slope of Saturation Vapour Pressure+Psychrometric Constant).

Let Others Know

✖

Facebook

Twitter

Copied!

: Value
: Unit

Penman's Equation Formula

Penman's Equation Example

Penman's Equation Solution

Penman's Equation Formula Elements

Other formulas in Evapotranspiration Equations category

How to Evaluate Penman's Equation?

FAQs on Penman's Equation

Variable Name