Lecture 2 ET

Question 1

what is evapotranspiration

Answer 1

transpiration +evaporation=ET

Question 2

definition for evaporation

Answer 2

liquid water converted to water vapour and removed from evaporating surface

Question 3

definition of transpiration

Answer 3

vapourisation of liquif water contained in plant tissue and vapour removal to atmosphere

Question 4

4 main impacts on Et

Answer 4

direct solar radiation
ambient air temp
air humididty
wind speed

Question 5

ET complicating factors (6)

Answer 5

shading
water avaliability
environmentla factors
managment
crop type 
crop development

Question 6

name 3 types of methods

Answer 6

blaney criddle
Penman
ASCE standard

Question 7

two ways radiation is lost

Answer 7

absorption by atmoshpere

reflection of clouds/gases

Question 8

what is the definition of a reference crop

Answer 8

a crop with an assumed height of 0.12m a surface resistance of 70 s m-1 and an albedo of 0.23
similar to grass

Question 9

assumptions of the blaney criddle method

Answer 9

assumes monthly air temp and sunshine ours are representative of the solar radiation

can overestimate or undersetimate ET

Question 10

penman assumes

Answer 10

medium-high radiation
medium high max humidity
moderate day wind double night wind