Topic 2: Atmospheric Water

Question 1

what is shortwave radiation expressed as

Answer 1

Qs or K

Question 2

what is longwave radiation expressed as

Answer 2

QL or L

Question 3

what does albedo replace in the net radiation equation?

Answer 3

outgoing shortwave

Question 4

explain sensible heat

Answer 4

QH: energy flows from warm to cold; via conduction or advection/convection

Question 5

explain latent heat

Answer 5

QE: energy transfer with phase change, consumed during evaporation, released during condensation

Question 6

physics of evaporation

Answer 6

• -evaporation does not require the surface to be at saturation, what matters is vertical gradient of vapour pressure
• -difference between two vapour pressures can be positive (evap occurring) or negative (deposition) or zero (neither occurring in a net sense)
• -if surface is snow or ice latent heat requires latent heat of fusion
• -evaporation rates are high when lots of energy available and atmosphere is dry and windy

Question 7

evaporation pan

Answer 7

measures the change in water height daily

Question 8

lysimeter

Answer 8

measure the change in weight of soil or snow sample

Question 9

water balance

Answer 9

can work well for small controlled basins. may also need to know about storage and precipitation. limitations: uncertainty in overall budget

Question 10

energy balance

Answer 10

theoretical calculation

Question 11

hydrological model: potential evapotranspiration

Answer 11

penman-montheith equation

Question 12

three ways to think of ET

Answer 12

actual evapotranspiration ET
potential evapotranspiration ET0
crop evapotranspiration CT

Question 13

what is PET

Answer 13

potential evapotranspiration; the rate at which ET would occur from a large area completely unlimited with supply of water

Question 14

impact of soil moisture

Answer 14

• -directly reduces available moisture at surface
• -decreases moisture in plants, increasing surface resistance
• -a function of soil type

Question 15

5 ways to describe humidity

Answer 15

1. vapour pressure (Pa or mbar)
2. mixing ratio (g H2O per kg dry air)
3. specific humidity (g H2O per kg air)
4. absolute humidity (g H2O per m3)
5. Relative humidity (%)

Question 16

does warm or cold air have lesser capacity to hold water vapour?

Answer 16

colder air

Question 17

what is Dalton’s Law

Answer 17

total pressure of a mixture of gases= sum of pressure of constituents

Question 18

actual vapour pressure vs saturation vapour pressure

Answer 18

actual: pressure resulting from the water molecules
saturation: partial pressure of the water molecules when air is saturated

Question 19

list the 4 precipitation processes

Answer 19

1. orographic uplift
2. frontal uplift
3. forced convergence
4. buoyant convection

Question 20

adiabatic processes

Answer 20

adiabatic cooling as air rises- no heat transfer with the environment.

Question 21

dry adiabatic lapse rate vs warm adiabatic lapse rate

Answer 21

dry is faster -9.8C/km

moist -6C/km

Question 22

how does a warm front work

Answer 22

buoyancy driven, warm wet air will rise over cold dry air

Question 23

how does a cold front work

Answer 23

cold air will wedge under warm air, causing more severe weather

Question 24

what is temperature advection

Answer 24

primary process that cyclones and anticyclones intensify, amplifies the shortwave making divergence and convergence stronger.