Discussion 3

Wednesday 2/13Quiz review + lectures 4-6

Quiz multiple choice

Most common gas?

• O2

• Ar• N2

• CO2

• He

Closest to the Earth?• Thermosphere

– Mesopause

• Mesosphere– Stratopause

• Stratosphere– Tropopause

• Troposphere• Earth

Quiz multiple choice

Stratospheric warming?• Density increases• Captures heat radiated from

Earth• Borders thermosphere• Contains ozone

• Thermosphere– Mesopause

• Mesosphere– Stratopause

• Stratosphere– Tropopause

• Troposphere• Earth

Essay redux – most common errors

Carbon cycle• Ocean both sink and source• Carbonates are a sink• Sinks and sources are NOT

in equilibrium– e.g. Keeling curve

Water cycle• Transpiration (or at least

one of the –ation’s)• Groundwater• Glaciers/ice caps• Biosphere

Lecture 4: Insolation

• Earth’s tilt & the seasons• Angle of incidence & solar zenith angle• Earth’s energy budget– Insolation and re-radiation– Latitudinal heat balance– The greenhouse effect

Fig. 2-12, p. 42

HEATING OF THE EARTH’S SURFACE DEPENDS ON THE AMOUNT OF SOLAR RADIATION PER UNIT AREA.

SAME AMOUNT OF RADIATION IS DISTRIBUTED OVER A LARGER AREA IN A THAN IN B.

RADIATION PER UNIT AREA IS LESS IN A THAN IN B. LESS HEATING IN A THAN IN B.

Latitudinal Heat Balance

20 )1( eA RQE

Simple Greenhouse Model

24 4 eeR RTE

4

)1( 04

Q

Te

But this doesn’t factor in the atmosphere! 254K vs 288K

Lecture 5+6: Temperature controls

• Diurnal cycle• Geographic controls– Latitude– Surface type– Elevation– Aspect

• Long-term control

– Cloud cover– Albedo– Ocean currents– Differential heating of

land and water

Miami

NYCChicago

STLDenver

Santa FeLA

Lecture 6: Heating, cooling,and stability

• Adiabatic processes• Equilibrium and lapse rates• Temperature Inversions• Wind Chill

• Ideal gas law: P=dR’T :: PV=nRT• Adiabatic process: no heat added or removed– P(Vγ)=const., T(Vγ-1)=const.

• Adiabatic lapse rate (T change with height)– Dry: ≈10oC / km (really 9.8)

– Wet: depends on water content, always less than dry rate; ≈6oC / km

Adiabatic Expansion and Compression

Equilibrium in

the atmosphere

Fig. 3-19, p. 75

Lifecycle of a nocturnal (radiative) temperature inversion

(A)Mid-afternoon

(B)Evening

(C)Sunrise

(D)Mid-morning

Fig. 3.12

Wind Chill Factor

• The wind chill factor describes the increased loss of heat by the body due to the movement of air.

• The wind causes an increased rate of evaporation of perspiration from the skin..

• It cannot be measured, so it is calculated• Wind chill equivalent temperature