Penman monteith equation

penman-monteith approach is the basis of this equation. it is used to calculate reference evapotranspiration for a particular area, there by we can calculate potential evapotranspiration

1. Satish Dulla-183350017
TD 602
1

2. ➢Evaporationandtranspirationbothdependsonsolar
radiation,airtemperature,relativehumidityandwindspeed.
➢Transpirationalsoaffectedbycropcharacteristics,
environmentalaspectsandcultivationpractices.
➢ReferenceEvapotranspiration:ETratefromauniform
surfaceofdense,activelygrowingvegetationhaving
specifiedheightandsurfaceresistance,notshortofsoil
waterrepresentinganexpanseofatleast100mofsameor
similarvegetations.
•Itistostudyevaporativedemandofatmosphere
independentofcroptype,developmentandmanagement.
•Wecanfixitforasurfaceandrelationcanbedeveloped.
2

3. 3

4. Rn=Net Radiation Flux(MJ / m²day)
G=Sensible heat flux into the soil(MJ / m²day)
=Mean saturation vapour pressure(kPa)
=Mean ambient vapour pressure(kPa)
=Psychromaticconstant (kPa/˚C)
=slope (first derivative of the function e(T))
4

5. 5

6. 6

7. 7

8. 8

9. 9

10. 10

11. 11

12. 12

13. 13

14. 14

15. 15

16. 16

17. 17

18. 18

19. 19

20. Lincoln Zotarelli, Michael D. Dukes, Consuelo C. Romero, Kati W. Migliaccio, and
Kelly T. Morgan . Step by Step Calculation of the Penman-Monteith
Evapotranspiration(FAO-56 Method)
http://www.tvrl.lth.se/fileadmin/tvrl/files/vvr145/Kompletterande_materialf4.pdf
REFERENCE
20