Lecture 15: Vegetation, soil moisture, evaporation and climate

Question 1

A Bowen ratio greater than 1

Answer 1

QH is the primary means of dissipating heat

Question 2

Bowen ration less than 1

Answer 2

Heat input to atmosphere primarily in latent form

Question 3

The pressure at which no further water can be entrained without condensation occuring

Answer 3

Saturation vapour pressure

Question 4

Amount of water vapour required to saturate air if temperature held constant

Answer 4

Saturation vapour pressure deficit

Question 5

Disadvantage to saturation vapour pressure deficit

Answer 5

Definition includes temperature, so difficult to compare VPD between locations

Question 6

The temperature at which saturation would occur if air cooled by removing heat. useful for determining whether dew (or frost, or fog) will occur

Answer 6

Dew Point Temperature

Question 7

The ratio between the actual amount of water in the air and the maximum amount it could hold at saturation - so is a function of both vapour pressure and temperature

Answer 7

Relative Humidity

Question 8

what can the following be used to measure - air temp, individual weather station thermometer, aggregated (interpolated) station data, remote sensing

Answer 8

Measuring QH

Question 9

Vapourisation of water from any surface eg grass, lake, building

Answer 9

Evaporation

Question 10

Release of water vapour by plants

Answer 10

Transpiration

Question 11

Calculating PET: Penman Monteith

Answer 11

Net radiation, vapour pressure gradient, windspeed

Question 12

Evaporation that would occur with an unlimited amount of water

Answer 12

Potential Evapotranspiration (PET)

Question 13

Low ET but high PET

Answer 13

Dry (hot) conditions

Question 14

ET and PET close to equal

Answer 14

Wet (cool) conditions