2. a) LATITUDE
Latitude refers to the distance a place is from the
equator.
The sun is over head at the equator all year round
but at the poles it is at a greater angle to the
ground.
The angle of incidence is greater at the poles as
compared to the equator.
EQUATOR:
• Sun travels a shorter distance therefore it loses
less heat due to scattering, reflection and
absorption. Heats a smaller surface area thus
places at the equator are hotter.
POLES
• Sun rays travel a greater distance and heats a
larger surface area therefore it is colder at the
poles.
3. Latitude also affects the length of SUMMER and WINTER
• In JANUARY – the south pole is tilted towards the sun
and it is summer in the southern hemisphere.
• In JANUARY – the north pole is tilted away from the
sun. It gets less heat therefore it is winter in the
northern hemisphere
• In JULY – the north pole is tilted towards the sun and it
is summer in the Northern Hemisphere
• In JULY – the south pole is tilted away from the sun
therefore it is winter in the southern hemisphere
• The equator remains the same distance away from the
sun all year round so areas along the equator have no
summer or winter.
4. b) THE SEA
• Sea has a high specific heat capacity ( amount of heat required to raise
the temperature of 1 unit of a substance by 10C)
• More heat is required to heat up water
• Sea conducts heat to greater depths
• It takes a long time to lose its heat
• The sea makes places near the coast warm in winter and cool in
summer
• These places have a MARITIME CLIMATE
• Land has a low specific heat capacity
• Less heat is required to heat up land because it is opaque
• Heat is only conducted to the surface of the soil
• Heat is lost very quickly
• Therefore the land is hot in summer and cold in winter.
• Places away from the sea are hot in summer and cold in winter
• These places have a CONTINENTAL CLIMATE
5. During the day the land heats up faster than the
sea.
A HP develops over the sea and a LP pressure
develops over the land
Air blows from HP to LP creating a SEA BREEZE
During the night the land loses heat faster
than the sea.
A HP develops over the land and a LP
develops over the sea.
Air blows from high pressure to low pressure
creating a LAND BREEZE
6. C) OCEAN CURRENTS
Coriolis force, causes the oceans to flow in
currents.
These currents flow clockwise in the northern
hemisphere and anticlockwise in the
southern hemisphere
Currents that flow from the equator to the
poles carry warm water towards the poles
Currents that flow from the poles towards the
equator carry cold water towards the equator.
7. As altitude increases temperature
decreases
REASONS:
• At higher altitudes Oxygen, CO2
and water vapor decreases.
• The air becomes less dense
(thin) (rarefied)
• Therefore heat easily escapes
Temperature decreases by
6,50C/1000meters (D.A.L.R)
d) ALTITUDE
8. e) CLOUDS
Reduces both incoming/outgoing solar radiation
Thick cloud – greater amount of
absorption/reflection/scattering
Therefore cloud reduces daytime energy
(reflecting, absorbing and scattering
insolation)
But it increases nighttime energy (absorbs/
reflects back long-wave radiation
from ground up)
9. F) WIND
Wind of different temperatures
change the temperature of the
receiving areas
Wind from the mountain –
usually cold
Wind from the sea – warmer in
the winter, colder in the summer
10.
11. Lesson objectives
• Be able to explain the difference between Absolute and Relative
humidity
• Be able to calculate relative Humidity using the relative humidity
chart
• Know the instruments that are used to measure relative humidity
12. Humidity refers to the amount of water vapor in the atmosphere
When the air contains the maximum amount of water vapor at a given temperature, the air is
saturated.
Absolute humidity (g of vapour/m3 of air)– Is the water content of air expressed in grams per
cubic metre. Air will be humid if it passes over water but dry if it releases all its water during
precipitation.
Relative Humidity is the amount of water vapor in the air expressed as a percentage of the
amount that would be present if the air was saturated.
a) HUMIDITY
13.
14. At 100% relative humidity, the air is saturated and the temperature at that
point is called DEW POINT TEMPERATURE.
The height at which a body of air reaches the DEW POINT is called the
CONDENSATION LEVEL.
Condensation is when air is cooled to its DEW POINT. This can happen in
THREE ways
• Radiation from the ground during a clear night
• Warm wind blowing over a cold ground
• Warm air meeting cold air
• Movement of air from water to colder latitudes
• Air moving up a mountain
15.
16.
17. Lesson objectives
• Be able to draw and explain the formation of
- Convectional rain
- Orographic rain
- Frontal rain
18. B) PRECIPITATION
Precipitation refers to any form of moisture in the atmosphere and it includes RAIN, SNOW,HAIL and DEW
RAIN
1. CONVECTIONAL RAIN
• Insolation warms the air above the
ground.
• The heated air rises.
• As it rises, it cools to DPT
• Condensation takes place and clouds
form.
• When the moisture in the clouds is to
heavy it comes down as rain called
convectional rain.
B) PRECIPITATION
Precipitation refers to any form of moisture in the atmosphere and it includes RAIN, SNOW,HAIL and DEW
RAIN
1. CONVECTIONAL RAIN
• Insolation warms the air above the
ground.
• The heated air rises.
• As it rises, it cools to DPT
• Condensation takes place and clouds
form.
• When the moisture in the clouds is to
heavy it comes down as rain called
convectional rain.
19. 2. OROGRAPHIC RAIN
• Warm air blows in from the sea
• The mountain (orographic barrier) forces
the air to rise.
• The air rises and cools to DPT.
• Condensation takes place and clouds
form.
• When the moisture in the cloud is to
heavy, it comes down or orographic rain.
20. 3FRONTAL RAIN (CYCLONIC RAIN)
• Warm and cold air masses meet
• The cold air sinks and wedges in underneath
the warm air and forces the warm air to rise.
• As the air rises, it cools to DPT.
• Condensation takes place and clouds form
• When the moisture in the clouds is to heavy,
it comes down as frontal rain.
21. Where do these rains occur on a global scale?
Orographic rain – generally occurs where there are mountains e.g. Rocky mountains, Andes Mountains,
Alps, etc.
Frontal rain – common in mid-latitudes where warm air is coming up from the tropics and it meets cold air
from the polar
regions. The weather system that results is called a MID-LATITUDE CYCLONE
Convectional rain is most common in equatorial and tropical regions which are hot.
Equatorial and mid-latitude areas are wet through out the year because they have low pressures all year
round.
The areas with the lowest rainfall are:
• In the subtropical HP belt such as the Sahara Desert
• Higher latitudes in the Northern Hemisphere
• In the rain shadow of the mountains e.g. Rocky mountains in North America and the Andes mountains in
South America
23. VOCABULARY/TERMINOLOGY
SUBLIMATION – when gas changes directly to a solid without passing through the liquid phase
CONDENSATION – Change from gas to liquid
DEW POINT TEMPERATURE – temperature at which condensation takes place
DEW – water droplets that have formed on cold surfaces
HYGROSCOPIC NUCLEI – salt, smoke and dust particles in the atmosphere onto which water vapor condenses
ATMOSPHERIC INSTABILITY – condition in the atmosphere in which air rises.
SATURATION POINT – point at which the relative humidity is 100%
HAIL – ice pellets that form in cumulonimbus clouds during thunderstorms.
24. SNOW
• When the temperature drops to below freezing point i.e.
below 00C, the water vapor (gas) changes directly into ice
(solid)
• This process is called sublimation
• The ice spicules unite into ice crystals.
• If condensation continues, these ice crystals become snow
flakes
• If the temperature close to the ground is very low, they will
reach the ground without melting, forming snow.
25. HAIL
• Hail generally develops during a
FRONTAL or CONVECTIONAL
THUNDERSTORM.
• In huge cumulonimbus clouds
updrafts carry water droplets to
temperatures below freezing point
and these water droplets freeze into
ice pellets.
• Downdrafts carry these ice pellets to
temperatures above 00C and more
water vapor condenses onto the ice
particles.
• Hail stones may rise and fall several
times in the atmosphere until they
are so large that they fall to the
ground as hail stones.
26. DEW
• If the air has a high humidity,
the skies are clear and the
atmosphere is calm (High
pressure conditions)
• Terrestrial radiation will cool
the ground and it will cool
the air immediately above
the ground to DEW POINT.
• Condensation will take place
close to the ground forming
Dew.
27. FOG
Fog is humid air that has fallen below the DEW POINT and condensation has formed a
dense cloud of water droplets forming a cloud that is close to the ground.
ACTIVITY
Study the diagram of FOG in your workbook and explain how each type of fog is formed.
CONSOLIDATION
Watch the following video on the formation of fog to consolidate your answer.
https://www.youtube.com/watch?v=lav0mpPpHMM
28.
29.
30.
31. LESSON OBJECTIVES
• Be able to explain what an urban heat island is
• Understand the difference in structure
between a rural and an urban area
• Explain the factors that are responsible for
the urban heat island
32. Urban heat island refers to the
fact that
the urban areas are warmer than
the
Surrounding rural areas
WHY????????
33. • Rural areas are made of vegetation and soil, which
has a higher specific heat capacity. Hence it takes a
longer time to heat up.
• The heat energy is also used by the plants to make
food by a photosynthesis
• Wide open spaces allow heat to easily escape
• Rural areas have more wet surfaces. Evaporation
cools the atmosphere
• Buildings are spaced far apart so there is no
obstruction to the wind.
• Limited amounts of artificial heating ensures that the
temperatures in the rural areas remain cool
• Urban areas is made up of tar, concrete, glass and
asphalt which has a lower specific heat capacity.
Hence urban areas heat up very quickly
• The glass acts as a green house and traps the long
wave radiation
• High building density creates a Canyon effect where
wind is channeled between buildings and does not
cool down the whole city.
• Large amount of traffic increases the heat
• High population density also increase the
temperature
• Artificial heating – from cars, industries and air
conditioners increases the temperature in the city.
35. DARK SURFACES IN A CITY E.G. ROADS AND BUILDINGS HAVE A LOWER ALBEDO THEY ABSORB MORE ENERGY
HENCE CITIES ARE WARMER.
RURAL AREAS ARE MADE UP OF GREEN VEGETATION WHICH HAS A HIGHER ALBEDO THERE THEY REFLECT MORE
ENERGY AND ARE COOLER
36. • Lines on a map showing places of equal temperature are called ISOTHERMS
• The city center (CBD) has the highest building density, highest population, the tallest buildings, and the most traffic
Therefore the CBD will have the highest temperature.
• As you move away from the CBD, the building density decreases, the population decreases, the height of the building
Decreases, the traffic decreases and the temperature starts to drop towards the rural areas.
37. HUMIDITY
Cities have a lower humidity than the surrounding rural
areas.
• High temperatures in the city lower the relative
humidity
• Precipitation is removed into storm water drains so
limited water for evaporation
• Limited vegetation in the city limits the amount of
transpiration which contributes to humidity
38. PRECIPITATION
Cities have a high precipitation
• High temperatures in the city causes air to rise.
• If the humidity is high convectional rain can occur
• Cities have dust and smoke particles released from cars
and factories which are hygroscopic nuclei onto which
water vapor condenses produces clouds and rain.
• Cities have less snow because temperatures are higher
and sublimation cannot occur.
