UNIT 2:

Heating of the atmosphere

Mrs. T. Herbst

Heating of the atmosphere

• Space and time

• Insolation spread through atmosphere

• Energy transferred from Earth’s surface

• Factors influencing temperatures at

different places

• The greenhouse effect

• Global warming

1. Temperature changes over

space and time

• Over Space

– Temperatures differ over the earth’s surface

• Hotter at Equator

• Colder at Poles

• Over time

– Nights colder, days warmer

– Winter colder, summer warmer

Topic 1 Unit 2 Activity 5

DOING RESEARCH, p51

Mrs. T. Herbst

Scale Designer Nationality Which

countries

use it?

Freezing

point temp

Boiling

point temp

° Celsius Anders

Celsius

Swedish South Africa

and most

other

countries

0°C 100°C

° Fahrenheit Daniel

Gabriel

Fahrenheit

German USA, Alaska 32°F 212°F

1. Two scales are used to measure temperature. Find

out about the people who developed these scales.

• Cape Town

• Today

– High 21°C

– Low 18°C

• Temperature range:

3°C

• Beaufort West

• Today:

– High 32°C

– Low 16°C

• Temperature range:

16°C

2. Use media sources to

compare daily temp. ranges.

2. Use media sources such as newspapers, radio

and TV to compare the daily temperature range in

places like Cape Town and Beaufort West. How

do you explain the differences you see?

– Cape Town – next to the ocean, Sun’s rays

penetrate deeper into water. Water heats and

cools slowly, so the temperature range is

smaller.

– Beaufort West far away from ocean. Land

heats and cools quickly, so the temperature

range is larger. (Only top few centimetres

heat up)

3. Study Fig. 39. Describe the main

seasonal temperature variations by

referring to specific temp. and regions

• The highest temperatures (20-30°C) are

found along the equator.

– Reason: Intense heating by direct sunrays

• Lowest temperatures (-50°C to -10°C) are

found at poles

– Reason: more terrestrial radiation than

insolation, (more scattering, reflection and

absorbtion of insolation)

4. Discuss the seasonal temperature

changes in SA. Refer to specific

temperatures and regions

• The average temperature (±15°C) of

South Africa’s coastal regions, is lower

than the interior and northern regions.

(±20°C) in summer =(Distance from

ocean causes warmer summer in the

interior/ cooler summer at coast)

3. Processes associated with the

heating of the atmosphere (Page 52)

• Sun is the source of nearly all heat energy

• Sun heats Earth through insolation.

• Then Earth becomes a radiating body

• Earth then gives off terrestrial radiation,

which is absorbed by the atmosphere.

• THIS IS THE HEAT THAT WE FEEL!

Processes associated with the

heating of the atmosphere

3.How is insolation (sun) spread

through the atmosphere?

• Absorption (66%)

– Water vapour, dust, gas, clouds

• Scattering (12%)

– dust and gas molecules

• Reflection (22%)

– Clouds, water and land surfaces

4. How is energy transferred from the

Earth’s surface? (Terrestrial radiation)

• Radiation

– Short-wave radiation reaches ground, changes to

long-wave radiation which heats the atmosphere

• Conduction

– In the 1st metre of atmosphere, energy moves from

molecule to molecule (packed together)

• Convection

– Moving molecules distribute heat, through strong

vertical movements by gas / liquid

Topic 1 Unit 2

Activity 6

Map Analysis and calculations

p53

Mrs. T. Herbst

1. What is the general trend in insolation

at the Earth’s surface as you move from

the Equator to the poles?

• A decrease in insolation as you move from

the equator to the poles.

– Reason: Equator receives direct

concentrated sunrays

• However, there is first an increase in

insolation towards the tropics, before there

is a decrease.

– Reason: “Turning around” of the direct rays

during the different solstices

The Sun is directly overhead at

"high-noon" on Summer Solstice

at the latitude called the Tropic of

Cancer.

The Sun is directly overhead at

"high-noon" on Winter Solstice at

the latitude called the Tropic of

Capricorn.

2. How does the average insolation in watts

per square metre over most of South Africa

differ from that over Patagonia

• South Africa: ±240 watts /sq.metre

• Patagonia: ±80 - 120 watts /sq.metre

– Reason: Patagonia's temperatures are

relatively cold for its latitude due to the

cold Malvinas Current and the high altitude.

• Source: Wikipedia

3. What natural feature is situated where

the areas of highest insolation on

continents are found?

• Deserts

– REASON: Deserts exist because of low

rainfall, thus less clouds.

– Less clouds = less absorption, scattering or

reflection of heat energy

4. Create a balance sheet that shows

what happens to the sun’s energy

radiated to Earth.

Earth’s Energy Balance

“Income” “Loss”

Insolation from sun 100% Reflected by clouds 20%

Scattered by air 6%

Reflected by water and

land surfaces

4%

Absorbed by clouds and

emitted to space

3%

Absorbed by greenhouse

gases and emitted to

space

16%

TOTAL LOSS 49%

NETT INSOLATION

(Absorbed by water and

land)

51%

4. Factors influencing temperatures

at different places (Page 54)

• Latitude

– Equator vs. Poles

• Altitude

– Height above sealevel

• Ocean currents

– Warm or cold ocean current

• Distance from the sea

Latitude

5.1 Latitude

5.2 Altitude

• Temperatures decrease the higher we go

up in the Troposhere

• Normal lapse rate (NLR) : 6.4°C / km

• Example:

– Mount Kilimanjaro at the equator (3 ̊South), covered with snow all year (height 5895 m above sea level)

– Town Moshi down the slopes: Annual

mean temperature 23,3 ̊C

5.3 Ocean Currents

Port Nolloth

on West

Coast:

MeanAnnual

Temperature:

14,2 ̊C

Durban on

East Coast:

Mean Annual

Temperature:

18.6 ̊C

5.4 Distance from the ocean

TOPIC 1 UNIT 2

ACTIVITY 7

DATA ANALYSIS AND ATLAS USE

P55

Mrs. T. Herbst

1.Use an atlas/map to find the positions of

the towns in this table. Complete the table

Place How far from Equator? How far from the sea?

Nairobi Near equator Far from sea

Harare Inside tropics Far from sea

Bloemfontein South of Tropic of

Capricorn

Far from sea

Cape Town Furthest from equator Situated on the coast

Durban South of Tropic of

Capricorn

Situated on the coast

Port Nolloth South of Tropic of

Capricorn

Situated on the coast

2. The first 3 places have an altutude of

around 1500m above sea level, but are

at different latitudes.

• Explain the pattern in their temperatures:

– They have a high temperature range because

they are far from the sea.

– The further away from equator, the cooler the

temperature

3. Why are the temperatures for

Bloemfontein and Port Nolloth different?

• Port Nolloth: Temperature range is small

– next to the sea (Maritime climate)

• Bloemfontein: Big temperature range, far

from sea (Continental climate)

4. Why are the temperatures for

Durban and Port Nolloth different?

• Durban: Summer AND Winter

temperatures are higher than Port Nolloth

– Reason: Warm Mozambique ocean current

on east coast next to Durban, Cold Benguela

ocean current next to Port Nolloth.

5. Climate Graphs (Page 56)

Topic 1 Unit 2

Activity 8

Read a climate graph

p56

1. What is the latitude of

Buenos Aires? (Atlas)

• 34° 36’ South

Figure 45

Temperature

Rainfall

2. Use fig. 45. Name the

following:

a) The 3 hottest months

a) November 23°C, December 23°C,

January 22°C

b) The 3 coldest months

b) May 11°C, June 10°C, July 9°C

3. Is Buenos Aires in a winter or

summer rainfall area?

• Neither summer nor winter rainfall area

– Reason: Receives rain throughout the year

with a maximum of 110mm in March.

(Southern Hemisphere Autumn), and 100mm

rain in Dec.

Topic 1 Unit 2

Activity 9

Draw a climate graph

p57

Mrs. T. Herbst

1. Draw a temperature graph using the

data in table 2 for Mossel Bay

Monthly Temperatures for Mossel Bay

MONTHS

2. Draw a rainfall graph for Mossel Bay,

using the data in table 2

MONTHS

3. What are the advantages of showing

climate data as a graph?

• It is easier to see patterns of temperature

and rainfall, quickly and easily.

4. Give one disadvantage of showing

climate data as a graph rather than

statistics.

• Data is rounded to the nearest ten in order

to draw a graph. So the graph is not as

accurate as the actual statistics.

5. Use an atlas to find the

latitudes of…

a) Mossel Bay:

– 34° 11 ‘ South

b) Tokyo:

– 35° 40’ North

6. Compare the climate of Mossel Bay

with Buenos Aires and Tokyo

Climate elements Mossel Bay Buenos Aires Tokyo

Amount of rainfall Min: 29-30mm to a

Max of 40mm

Min: 60mm to a

Max of 110mm

Min: 50mm to a

Max of 240mm

Monthly

distribution

Throughout the

year, with most at

equinoxes

Throughout the

year with most in

March

Minimum in

January, Maximum

in Sept

Maximum Temp. 21°C 23°C 26°C

Warmest Months Jan; Feb Nov; Dec August

Season Summer Summer Summer

Minimum Temp. 15°C 9°C 3°C

Coldest Months Jul, Aug, Sept July January

Season Winter Winter Winter

Comparison of data: Buenos

Aires and Mossel Bay.

• a)Although Buenos Aires gets much more

rainfall than Mossel Bay, it is spread in a similar

way throughout the months of the year.

• Max temperatures in Buenos Airesare only 2 °C

higher than Mossel Bay, but they are

experienced two months earlier in the summer.

• Mossel Bay remains warmer in winter with a

temperature of 15 °C compared to Buenos Aires’

monthly temperature in July which is 6°C lower.

Comparison of data (Tokyo and

Mossel Bay)

• b) Tokyo gets 6 times more rain than Mossel

Bay. The rain shows a clear minimum in

January, increasing steadily until September,

then decreasing again.

• The maximum summer temperature occurs in

August in Tokyo, when it is 5 °C higher than

Mossel Bay’s summer maximum of 21 °C.

• Mossel Bay remains much warmer in winter with

a minimum temperature of 15 °C, compared to

Tokyo’s minimum January temperature of 3 °C

(12 °C lower)

6. The greenhouse effect (Page 58)

• Atmosphere allows insolation in…

• ..but then traps outgoing terrestrial

radiation by gases such as CO2 and water

vapour

• = “Natural Greenhouse effect”

• Warms atmosphere

The greenhouse effect

• Human activities have increased the

amount of greenhouse gases

• = “Enhanced greenhouse effect”

• Will cause a gradual increase in Earth’s

average atmospheric temperatures =

Global warming

Greenhouse effect

How can greenhouse gases be

reduced?

Topic 1 Unit 2

Activity 10

The Greenhouse gases

p60

Mrs. T. Herbst

1) Short Wave

radiation: (UV)

passes directly

through the

greenhouse gases

4) As more heat is

retained , the

earth’s atmosphere

will become warmer

3) CO2: Released by

factories, exhausts,

animals

Water vapour: From

evaporation of water

Methane: when

bacteria break down

(fermentation)

Nitrous Oxide: Fossil

fuels, power stations,

exhausts, fertilisers

CFC’s: Aerosols, air

conditioners,

refrigerators

2) Long-wave

radiation (infrared) is

either absorbed by the

greenhouse gases or

re-radiated back to

earth’s surface

Blanket effect of greenhouse gases

EARTH’s SURFACE

GREENHOUSE GASES

7. Global Warming – Evidence? (Page

61)

How do greenhouse gases

cause global warming?

8. Possible impact on climate

change in Africa (Page 62)

• Possible temp. increase of 4°C by 2080

– As much as +7°C in South and +8°C in North

• Rising sea levels

– Drastic effects on populated low-lying areas

• Climate changes: Extreme droughts,

followed by heavy rainfall = desert

expansion DESERTIFICATION

Possible impact on climate

change in Africa continued..

• Change of weather patterns = failure of

crops

• Migration of animals and people to avoid

deserts (increasing aridity)

• Extinction of animals and plants due to

habitat change

• Flooding

• Conflict (war) over scarce resources

Topic 1 Unit 2

Activity 11

Data Analysis and

research

p63

Mrs. T. Herbst

1. Why has there been an increase

in carbon dioxide production?

• Increased industrial activities

• Burning of fossil fuels increase

• More production of cement

• Burning of vegetation to clear

land

• All of the above as a result of the

increasing global population.

2. Describe AND explain the relationship between

the carbon dioxide levels and the global average

temperature over the time period

• With the constant rise of CO2,

temperature also rise.

• Increase in human activities,

increases greenhouse gases,

which absorbs more heat. Heat

does not escape = enhanced

greenhouse effect

3. How can Africa be affected

by Global warming?• Rise in sea levels: South Coast of

Senegal, Lagos, Nile delta: Loss of

coastal land, population relocate

• Desertification: East Africa and Sahel :

People will have to relocate

• Drought: Sahara / SA: Significant

decrease in rainfall, and harvests

• Floods: East and West Africa: People

displaced, increase in waterborne

diseases (cholera)

• Conflict over resources: Resources

become scarce due to climate change,

people start to fight about the resources –

food shortages in Sub-Sahara Africa

4.

Kyoto Protocol• Where: Kyoto, Japan

• When: 16 Feb 2005

• Which countries: Europe, all UN

members, except Andorra, Canada, South

Sudan and USA

Revision UNIT 2 page 65

Answers

1.

Unit 2 Answers continued

2a) Insolation / Solar radiation

b) Sun: Short waves; Earth: Long waves

Reason: Only light (white) heat from

sun reaches earth, and light waves are

short. Earth absorbs these short waves, and

returns it to the atmosphere in the form of

infrared radiation, which are long waves.

(invisible to naked eye)

• c) Radiation

– Short-wave radiation reaches ground, changes to

long-wave radiation which heats the atmosphere

• Conduction

– In the 1st metre of atmosphere, energy moves from

molecule to molecule (packed together)

• Convection

– Moving molecules distribute heat, through strong

vertical movements by gas / liquid

d)

e)

• f) Possible temp. increase of 4°C by 2080

– As much as +7°C in South and +8°C in North

• Rising sea levels

– Drastic effects on populated low-lying areas

• Climate changes: Extreme droughts,

followed by heavy rainfall = desert

expansion

• Change of weather patterns = failure of

crops

• Migration of animals and people to avoid

deserts (increasing aridity)

• Extinction of animals and plants due to

habitat change

• Flooding

• Conflict (war) over scarce resources