Sub-Synoptic scale process - Climatology

Question 1

Mesoscale phenomena

Answer 1

Part of a continuum of atmospheric motion - spatial size range is 10 - 200km, with a time scale of a few hours to a few days

Question 2

Mesoscale phenomena can be separated into two broad groups depending on their origin

Answer 2

1. Free atmosphere processes
2. Thermal and mechanical effects of the surface - surface induced processes

Question 3

Two aspects of earths surface that lead to development of mesoscale weather processes

Answer 3

1. Physical character of the surface - Orographic forcing
2. spatial variability of the surface energy balance - Thermal forcing

Question 4

In stable situations air tends to get blocked and flows around an obstacle.
What happens with decreasing stability.

Answer 4

More and more air passes over the obstacle and forms lee waves

Question 5

Measure for the amount of blocking:

Answer 5

Froude number

Question 6

Froude number equation

Answer 6

Froude number = pi(horizontal wind speed/stability of the atmosphere x width of the obstacle

Question 7

Four types of foehn effect

Answer 7

1. Stable foehn
2. Unstable foehn
3. Low-level blocking
4. The typical bora

Question 8

Bora

Answer 8

Cold, dry gusty wind that occurs when cold air is trapped below an inversion

Question 9

Most common dynamic mesoscale feature created by mountains

Answer 9

Foehn effect

Question 10

Temperature change with height for non-saturated air (1 degree per 100m)

Answer 10

Dry adiabatic lapse rate (DALR)

Question 11

Temperature change with height for saturated air (0.4 - 0.8 per 100m)

Answer 11

Saturated (moist) adiabatic lapse rate (SALR)

Question 12

Foehn effect results

Answer 12

Precipitation on the windward side of a mountain range and a drying effect on the leeward side

Question 13

Foehn effect process

Answer 13

1. Moisture lost through precipitation on the windward side
2. Consequently, the condensation level on the lee side is at a higher level
3. This results in longer dry adiabatic warming on the lee side
4. Therefore, at the same altitude, air on the lee side is warmer than on the windward side

Question 14

Two thermal effects on horizontal airflow

Answer 14

1. Land-sea breeze system
2. Mountain valley winds

Question 15

Boundary layer

Answer 15

The region of the atmosphere that is directly influenced by the surface beneath it

Question 16

Layers of the atmospheric boundary layer (ABL)

Answer 16

1. Outer layer
2. Turbulent surface layer
3. Roughness layer
4. Laminar boundary layer
5. Sub surface layer

Question 17

Outer layer (ABL)

Answer 17

The remaining turbulent layer that extends to the top of the ABL

Question 18

Turbulent surface layer

Answer 18

Immediately above the surface elements, small-scale turbulence dominates

Question 19

Roughness layer

Answer 19

Strongly influenced by the roughness elements, complex 3-d flows around them

Question 20

Laminar boundary layer

Answer 20

Molecular diffusion

Question 21

Sub surface layer

Answer 21

Molecular diffusion of heat away from the ground

Question 22

Four primary forms of energy

Answer 22

1. Radiant energy (electromagnetic waves)
2. Thermal energy (energy possessed by a body as a consequence of its sensible/latent heat content)
3. Kinetic energy (energy of motion)
4. Potential energy (energy that a body possesses as a result of its position in gravity

Question 23

Flow rate of mass

Answer 23

Mass flux

Question 24

Flow rate of mass per unit (surface) area

Answer 24

Mass flux density

Question 25

Rate of work/flow rate of energy

Answer 25

Power,heat flux

Question 26

Flow rate of energy per unit (surface) area

Answer 26

Heat flux density

Question 27

Flow rate of radiative energy per unit (surface) area

Answer 27

Radiant flux density

Question 28

Three modes of energy exchange

Answer 28

1. Radiation - electromagnetic waves 2. Conduction - molecular motion 3. Convection - mass movement in a fluid

Question 29

Net all-wave radiation

Answer 29

The amount of all-wave radiant energy that is available at a surface, which is then partitioned into different energy balance components

Question 30

Net all-wave radiation equation

Answer 30

Net all-wave radiation = net shortwave radiation + net longwave radiation

Question 31

Most important link between energy and water balance

Answer 31

Latent heat flux - evaporation and condensation at the surface results in mass loss or gain of water

Question 32

Input/output of a glacier terms: Accumulation - Ablation -

Answer 32

Accumulation - Snow/ice gain e.g snowfall, rainfall, superimposed ice Ablation - Snow/ice loss e.g Surface melt, basal and englacial melt, evaporation, sublimation, calving and avalanching

Question 33

How does ice and snow compare with radiation exchanges on glaciers

Answer 33

Albedo of snow is higher than ice, meaning once a glacier loses its snow in the summer, it absorbs more energy and melts faster.

Question 34

How much melting occurs in summer on a glacier in the ablation zone

Answer 34

30-40mm

Question 35

High and low ablation events are associated with which wind direction

Answer 35

North-west South west