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Flashcards in The Earth System Recap Deck (28)
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1
Q

What does the climate system refer to?

A

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

2
Q

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

A

The atmosphere

3
Q

Atmospheric processes have a direct impact on human activities…

A

Agriculture, water resources, extreme weather events.

4
Q

Humans have interacted with atmospheric processes by…

A

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

5
Q

Seasonal differences in climate across the globe are caused by…

A

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

6
Q

What are the seasons called?

A
September 23 (Autumnal Equinox)
June 22 (Summer Solstice)
March 21 (Vernal Equinox)
December 22 (Winter Solstice)
7
Q

Wind systems- annual and seasonal variations are caused by…

A

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

8
Q

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

A

Heat transfers.

9
Q

What is convection?

A

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

10
Q

What is adiabatic motion?

A

Temperature changes occur with vertical motions in the atmosphere

11
Q

Why is the atmosphere continually turning?

A

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

12
Q

Where does atmospheric overturning occur?

A

In the troposhere

13
Q

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

A

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

14
Q

What is the dry adiabatic lapse rate?

A

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

15
Q

What is the saturated adiabatic lapse rate?

A

Lapse rate in the presence of condensation

16
Q

What is the coriolis effect?

A
  • 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)
17
Q

What are geostrophic winds?

A
  • 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
18
Q

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

A

Hadley cell
Ferrel cell
Polar cell

19
Q

What are jet streams?

A

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

20
Q

What is the Subtropical westerly jet stream?

A

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

21
Q

What is the polar front jet stream?

A

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

22
Q

What are Rossby waves?

A

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

23
Q

Why are Rossby waves important?

A

They strongly influence the formation and subsequent

evolution of surface weather features

24
Q

Where do middle-latitude frontal depressions form?

A

Grow rapidly just downwind of upper troughs of

Rossby waves

25
Q

Where do anticyclones form?

A

Just downwind of upper ridges

26
Q

Rossby waves
Differences between the hemispheres
Southern temperate-latitudes

A

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

27
Q

Rossby waves
Differences between the hemispheres
Northern temperate-latitudes

A

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

28
Q

Summary

A
  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.