Lecture 11 - A World of Changing Environments

Question 1

What is the Definition of Weather?

Answer 1

-The atmospheric conditions of any place for a short period of time (temporary changes in the climate)

Question 2

What is the Definition of Climate?

Answer 2

-Average of the day-to-day weather conditions over a long period of time (usually at least 30 years)

Question 3

What Factors define a System?

Answer 3

-Have a structure/ organisation
-Are generalisation of the world
-Facilitate the flow of energy/ material
-Show functional and structural relationships between their components

Question 4

What are the Different types of Systems?

Answer 4

-Open system = allows flow of mass/ energy through a boundary
-Closed system = allows energy but NOT mass to flow through a boundary
-Isolated system = allows no mass or energy to flow through a boundary

Question 5

What are Couplings?

Answer 5

-Positive = and increase causes an increase
-Negative = an increase causes a decrease and vice versa

Question 6

What are Feedback Loops?

Answer 6

-Positive = disturbances are amplified (they are usually unstable)
-Negative = tend to diminish the effect of disturbances (normally stable)

Question 7

What is meant by Equilibrium?

Answer 7

-A state of balance in a system due to an external action of opposing forces (represented by a negative feedback loop or a stable relationship)

Question 8

Explain the Atmosphere’s Role in the Climate

Answer 8

-46% of solar radiation is absorbed by the Earth’s surface
-23% absorbed on the atmosphere by water vapour and clouds (lower altitude) and by ozone at higher altitudes
-It acts as a radiative blanket hindering the loss of heat to space

Question 9

Describe the Troposphere

Answer 9

-Vertical and horizontal mixing is common and there is a highly variable water vapour content
-This is the lowest boundary/ the planetary boundary

-The highest point is the tropopause:
-main jet streams here
-height varies controlled by
surface energy exchange
-Highest at equator (17km) and
lowest at poles (9km)

Question 10

Describe the Stratosphere

Answer 10

-8-17-50km
-Temperature remains fairly constant with low mixing
-Temperature can increase due to stratospheric thermal inversion
-Ozone is 320ppb here compared to only 34 in the troposphere
-This ozone heats this layer as it absorbs energy from incoming UV radiation

Question 11

Describe the Mesosphere

Answer 11

-50-80km
-Temperature here decreases with altitude
-75C to -90C (coldest layer in the atmosphere)
-Mesopause separates the mesosphere from the thermosphere
-Also separates the homosphere (where gasses are well mixed) from the heterosphere (where gasses start separating by mass)

Question 12

Describe the Thermosphere and Exosphere

Answer 12

-At around 100km
-Extreme low pressure (<0.0002 hPa)
-Temperature can rise to 100s of C depending on solar radiation
-The exosphere is the uppermost layer and is the transition between interplanetary/ space