The Earth System Recap

Question 1

What does the climate system refer to?

Answer 1

An interactive system consisting of the atmosphere, hydrosphere, cryosphere, the land surface and the biosphere.

Question 2

What is the most unstable and rapidly changing part of the climate system?

Answer 2

The atmosphere

Question 3

Atmospheric processes have a direct impact on human activities…

Answer 3

Agriculture, water resources, extreme weather events.

Question 4

Humans have interacted with atmospheric processes by…

Answer 4

Changing land cover, burning fossil fuels and adding important trace gases.

Question 5

Seasonal differences in climate across the globe are caused by…

Answer 5

The spherical shape of the Earth- large N-S temperature differences.
Tilt of the Earth’s axis of rotation (23.5o)

Question 6

What are the seasons called?

Answer 6

September 23 (Autumnal Equinox)
June 22 (Summer Solstice)
March 21 (Vernal Equinox)
December 22 (Winter Solstice)

Question 7

Wind systems- annual and seasonal variations are caused by…

Answer 7

Inequalities in the distribution of solar radiation over the Earth’s surface.
The Earth’s rotation.

Question 8

Energy surplus at the equator and deficit at the poles leads to…

Answer 8

Heat transfers.

Question 9

What is convection?

Answer 9

The dominant process for transferring heat upwards from the Earth’s surface.

Question 10

What is adiabatic motion?

Answer 10

Temperature changes occur with vertical motions in the atmosphere

Question 11

Why is the atmosphere continually turning?

Answer 11

Mass balance dictates that as some air masses rise some must also fall.

Question 12

Where does atmospheric overturning occur?

Answer 12

In the troposhere

Question 13

Over long timescales the complete Earth–atmosphere system is in thermal equilibrium

Answer 13

Heat energy is transferred from the tropics to poles by the north–south circulations in the atmosphere and oceans

Question 14

What is the dry adiabatic lapse rate?

Answer 14

Rate of temperature fall with height in a rising parcel of air (9.8oC per km)

Question 15

What is the saturated adiabatic lapse rate?

Answer 15

Lapse rate in the presence of condensation

Question 16

What is the coriolis effect?

Answer 16

• Air should move 90° to isobars but is deflected by the
  force of the Earths’ rotation
• Observations show air flow is almost parallel to the
  isobars (except very near to the surface and at the
  equator)

Question 17

What are geostrophic winds?

Answer 17

• Deflected winds >1km above the surface
• Speed is proportional to pressure gradient and strength
  of coriolis effect
• Airflow is anticlockwise around low pressure in the N
  hemisphere and the converse for the S hemisphere

Question 18

3-cell atmospheric circulation model in each hemisphere (controlled by a pressure
gradient force)

Answer 18

Hadley cell
Ferrel cell
Polar cell

Question 19

What are jet streams?

Answer 19

Fast-moving bands of air embedded in Rossby waves caused by sharp temperature differences (speeds up to 140 kms-1)

Question 20

What is the Subtropical westerly jet stream?

Answer 20

Poleward boundary of the tropical Hadley cell
Just below tropopause
In winter it divides around the Tibetan Plateau

Question 21

What is the polar front jet stream?

Answer 21

Associated with the warm and cold fronts of temperate-latitude depressions
Considerable day-to-day variation

Question 22

What are Rossby waves?

Answer 22

Middle-latitude the atmosphere is highly disturbed (Ferrel cell is largely schematic)
Surface air circulation- irregularly shaped,
eastward-drifting, cyclonic and anticyclonic systems
Higher atmosphere – smooth wave-shaped patterns

Question 23

Why are Rossby waves important?

Answer 23

They strongly influence the formation and subsequent

evolution of surface weather features

Question 24

Where do middle-latitude frontal depressions form?

Answer 24

Grow rapidly just downwind of upper troughs of

Rossby waves

Question 25

Where do anticyclones form?

Answer 25

Just downwind of upper ridges

Question 26

Rossby waves
Differences between the hemispheres
Southern temperate-latitudes

Answer 26

Rossby waves could arise anywhere in the middle latitudes due to ocean cover

Question 27

Rossby waves
Differences between the hemispheres
Northern temperate-latitudes

Answer 27

Preferred locations, because influenced by thermal properties of land and sea and the location of key mountain ranges (Rockies and Himalayas)

Question 28

Summary

Answer 28

1. Energy surplus at the equator and deficit at the poles leads to heat transfers.
2. The large-scale circulation of the atmosphere is organised into cells.
3. Jet streams form at the boundaries of the cells and play a major role in storm development.
4. Jet streams form into standing waves that affect the positions of major air masses.