Lecture 8

Question 1

The pressure difference between the Icelandic low and Bermuda high is important to?

Answer 1

European severity

Question 2

What’s the zone where trade winds converge?

Answer 2

Inter-tropical convergence zone (ITCZ)

Question 3

Monsoon climate

Answer 3

Refers to the reversal of mean surface wind direction from summer to winter

Most regions between 35 N + 25 S and between 30 W + 170 E experience monsoon climate (best known in S + SE Asia)

Question 4

What is responsible for the relatively mild climates of western and Northern Europe?

Answer 4

The North Atlantic Current (the ‘Gulf stream’)

Question 5

What is the influence of the Himalayas?

Answer 5

They cast an extensive rain shadow comprising the Tibetan Plateu + the Taklamakan desert

Question 6

What are the 7 factors that determine climate?

Answer 6

Latitude - determines how much average solar radiation a given location receives, which impacts seasonality
Land and water - determines continentality of a given location
Ocean currents - can provide e.g. An additional heat source for a region
Prevailing winds - determine e.g. How much moisture is advected + hence determine potential for rainfall
Pressure cells - determine availability of cloud coverage and frontal systems
Mountain barriers - can deflect wind or result in rain shadow on the leeward side
Altitude - has an influence on temperature

Question 7

What is climate?

Answer 7

Long term averages of weather conditions and the range of variability with respect to the mean value

Question 8

What is Weather?

Answer 8

Described through temperature, pressure, rainfall, visibility and cloud coverage

Current physical state of the atmosphere

Question 9

What are the two systems of climate classification?

Answer 9

Thornthwaite - based on moisture (soil and ET), used mainly by scientists
Koppen system - based on temperature and precipitation, linked to vegetation (tropical moist, dry, moist-mid latitude with severe/mild winters, polar climates)

Question 10

What largely determines average wind and pressure distribution?

Answer 10

Semi-permanent highs and lows

Question 11

What causes climate variability?

Answer 11

Caused by natural changes in climate that fall within the normal range of extremes for a particular region
Measured by: temperature, precipitation and frequency of events
Atmospheric oscillations = important driver for natural climate variability

Question 12

What is the positive phase of the North Atlantic oscillation?

Answer 12

Stronger than usual pressure difference.

Fast storm tracks bring wet warm winters in W.Europe, mild and wet winters on N. American East Coast

Question 13

What is the negative phase of the North Atlantic oscillation?

Answer 13

Weaker pressure difference

More cold air invasions on N. American East Coast and in Mediterranean Europe

Question 14

What is the North Atlantic oscillation?

Answer 14

Defined as the difference between sea level pressure between 2 stations during the winter season (dec-mar)

Question 15

What two pressure cells are involved in the North Atlantic oscillation ?

Answer 15

Icelandic low pressure cell

Azores-Bermuda high pressure cell

Question 16

Name the environmental spheres?

Answer 16

Lithosphere, biosphere, hydrosphere, atmosphere

Question 17

The environmental spheres of the earth/climate system interact through feedbacks, what are they and what do they cause?

Answer 17

Positive - instability, change accelerates

Negative - stability, change slows down

Question 18

The strength of a feedback on temperature is called ?

Answer 18

Feedback factor and is defined:

F = (temperature change with feedback)/ (temperature change without feedback)

If F has the value of 1, no feedback exists

Question 19

Why should we be bothered about climate change?

Answer 19

Environmental problems and harm it may bring
Our way of life is fairly dependent on certain range of climatic conditions, even though technological advancements have slightly reduced this independence
Effects ecological processes and ecosystems
Natural climate variability (e.g. El Niño/droughts) causes economic loss and suffering

Question 20

What natural variability influences the global average surface temperature?

Answer 20

Changes in incoming solar radiation (orbital changes, solar outputs)
Continental drift (affects thermohaline circulation, rate of chemical weathering) 
Changes in earths albedo (volcanic winter, polar ice caps)
Changes in outgoing terrestrial radiation (increased GHG effect)

Question 21

Milankovitch cycle

Answer 21

3 most common orbital changes
Changes in eccentricity - varies 100,000yrs
Variations in obliquity - between 21.6 + 24.5 degrees, over 41,000yrs
Changes in precession and point of perihelion - 23,000yrs
Currently the earth is closest to the sun in January - in 11,000yrs the perihelion point = July

Question 22

Ice core records at 3500m depth show…

Answer 22

Atmospheric records dating back almost 700,000 years BP