Weather Tropical rain forests, deserts

1. Weather and Climate

2. Weather and Climate
• Weather is the current state of the
atmosphere (rain, temperature, wind, cloud
cover, humidity etc)
• Climate is the condition of the atmosphere in
a region over a period of time (year)

5. Weather equipment
Stevenson’s screen
• A Stevenson screen is a white louvered wooden
box.
• It contains some weather equipment like
thermometers and barometers.
• The Stevenson screen is white to reflect sunlight
and has slats to allow air to circulate easily.
• The Stevenson screen should be placed above the
ground and away from the buildings to take
accurate readings of the air, rather than direct
sunlight or heat from the ground or from
buildings

6. Barometer

7. Barometer
• Barometers are used to measure air pressure
(in millibars).
• Barometers are normally kept inside
Stevenson screens to keep them safe.
• A barometer has a movable needle (pointer)
which can be moved to the current reading so
that you can then make a comparison with the
reading from the following day.

8. A Digital barometer

9. Max./Min. Thermometer or Six’s
Thermometer
• A maximum and minimum thermometer
records the maximum temperature of the day
and the minimum temperature of the day
(diurnal range).

10. Digital Max./Min Thermometer

11. Wet/Dry Bulb Thermometer
(Hygrometer)

12. Wet/ Dry (Hygrometer) Digital

13. • A hygrometer measures the humidity of the air.
Humidity is the amount of moisture (water
vapour) in the air.
• A hygrometer has two thermometers, a dry one
and a wet.
• Humidity is measured by using a table that looks
at the difference between the wet bulb and the
dry bulb.
• A hygrometer can also be used to find dew point.

18. Anemometer

19. • Anemometers measure wind speed.
• Wind speed is normally measured in mph or
kph, but can also be measured in m/s (metres
a second).
• Digital anemometers are more accurate.
• Anemometers are normally placed on top of
buildings so that they are not protected from
the wind and so they don't experience
channeling of wind

20. Rain gauge
• Rain gauges are used to measure rainfall.
Rainfall is normally measured in millimetres.
Rain gauges should be placed on grass,
because if they are placed on concrete, extra
water can splash into them. Rain gauges
should also be checked regularly to avoid
evaporation.

21. Rain gauge

23. Wind vane

24. Wind vane
• Wind vanes are used to check the direction of the
wind.
• Compass points are used to give wind direction.
• Wind is measured in the direction that the wind
is coming from.
• Wind vanes are often placed on top of buildings
so that they are fully exposed to the wind.
• When using a wind vane you need to use a
compass to make sure that it is properly aligned.

25. Cloud cover
• Cloud cover (also known as cloudiness,
cloudage, or cloud amount) refers to the
fraction of the sky obscured by clouds when
observed from a particular location. Okta is
the usual unit of measurement of the cloud
cover.
• This is made by a visual assessment of how
much of the sky is covered by cloud.

27. Measuring the cloud cover

28. • To calculate cloud cover a mirror is often used.
• You divide the mirror into squares and then
place the mirror on the ground.
• The mirror will reflect the clouds and you can
count the number of squares covered or
partially covered by cloud.
• You can do this as a percentage or convert to
oktas which is the normal measurement of
cloud cover.

29. Sunshine recorder
• A sunshine recorder is a device that records the
amount of sunshine at a given location. The
results provide information about the weather
and climate as well as the temperature of a
geographical area.
• Sunshine recorder consists of a glass sphere
mounted in a spherical bowl and a metallic
groove which holds a record card. Sun's rays are
refracted and focused sharply on the record card
beneath the glass sphere, leaving burnt marks on
the card.

32. Explain the uses of the following
equipment
1. Stevenson screen
2. Barometer
3. Max/Min Thermometer
4. Wet/ Dry bulb thermometer
5. Anemometer
6. Rain gauge
7. Wind vane
8. Sunshine recorder

33. Cloud types

34. Cumulus

38. High clouds

39. Medium clouds

40. Low clouds

42. Climate Graphs and Weather Maps

45. Fig.10 daily weather

48. Rain shadow region

50. Equatorial region

51. Equatorial weather

52. Equatorial weather: Brazil

55. Distribution of deserts

56. Hot desert

57. Dubai

61. Factors affecting climate
• Latitude: Places in the tropics (between the
Tropic of Cancer and Tropic of Capricorn) are
much warmer than places furthest away near the
poles. This is because the sun is more overhead in
areas nearest the equator.
• Distance from the sea: The sea takes longer to
warm than land, so places near the sea are cooler
in the summer because the sea cools them.
However, the sea retains the heat better than the
land so places near the sea are warmer in the
winter because the sea warms them.

62. • Prevailing winds: If the prevailing wind is from
the poles then the temperature will be lower,
but if the prevailing wind is from the tropics
then the temperature will be higher.
• Ocean currents Hot ocean currents tends to
warm winters and cold ones cool summers.
The UK benefits from a warm ocean current
travelling from the Gulf of Mexico.

63. • Altitude: Temperatures on average decrease 1
degree Celsius for every 100 meters gained.
This means that some places near the Equator
e.g. the Andes in Ecuador can be covered in
snow all year.
• Cloud cover: high cloud cover reduces
temperature and low cloud cover increases.

64. Ecosystems
• Tropical rainforests are found on or near the
Equator (roughly between 28 degrees north
and south).

65. Tropical rainforest distribution

66. Tropical vegetation

67. • Emergents: Emergents are tall trees that grow
above the canopy
• Canopy: The canopy layer contains about 50%
of the rainforests wildlife.
• Shrub Layer: The shrub layer is near the forest
floor and is also extremely dense.

69. Importance of tropical rainforests
• Biodiversity: contain 50% of flora and fauna
• Photosynthesis: they are the lungs of the
earth
• Prevents soil erosion and flood
• Economic value: provides wood, medicines,
food.
• Habitat for indigenous people.
• Controls climate

70. Reasons for rainforest deforestation
• Subsistence farming and farming techniques
• Hydro electric projects
• Mining
• Cattle ranching
• Population growth
• Tourism
• Illegal logging

71. Problems of deforestation
• Flooding
• Landslides
• Biodiversity lost
• Silting of rivers, seas and oceans
• Desertification
• Reduced rainfall
• Climate change

72. Tropical rainforest animals

74. Protecting rainforests
• Creation of national parks
• Sustainable forestry
• Promoting ecotourism
• Ban the sale of rain forest products
• Educating people about the ill effects
•

75. Rainforest case study: Amazon
rainforest

76. Amazon rainforest facts:
• It is home to 1000 species of bird and 60,000
species of plants
• 10 million species of insects live in the Amazon
• It is home to 20 million people, who use the
wood, cut down trees for farms and for cattle.
• It covers 2.1 million square miles of land
• The Amazon is home to almost 20% of species on
Earth
• The UK and Ireland would fit into the Amazon 17
times!

77. Deforestation in Amazon
• An area of rainforest the size of Belgium was
being cut down every year.
• Brazil has over 60% of Amazon rain forests.
• Cattle ranching, agriculture (both small scale
and large scale), and logging are major
reasons.
• If no action taken, at current rate of
deforestation, the Amazon rainforest would be
reduced by 40% in two decades.

79. Desert climate
• Deserts are extremely dry (arid) places.
Deserts normally have less than 250mm a year
• Because there is no moisture in the air, there
are very few clouds in deserts which means
desert have high levels of incoming radiation
from the sun.
• Daytime temperature is very high and night
time temperature (diurnal) is very low in the
deserts.

82. Desert Fauna and Flora

85. How plants adapt
• Fat and fleshy leaves, roots and trunks can
store water.
• Some plants live very short to take advantage
of the wet season.
• They have long wide roots to absorb more
water
• They have spiky and waxy surface to protect
themselves from enemies.

86. Animal adaptation
• Nocturnal: active only at night, hide in
burrows during day.
• Have large ears to cool body
• Adopt dormancy
• Migrate during the hottest season

88. Case Study: An area of hot desert
• The Sahel region – Desertification

89. The Sahel
• The Sahel is an area of land south of the Sahara,
running from Mauritania in the west, through
Niger, Burkina Faso, Mali, Chad, Sudan and across
to Ethiopian in the west.
• The vegetation is mainly savanna (grassland) with
some areas of woodland and shrub land and
people are traditional semi-nomadic herders.
• In recent years the Sahel has been suffering from
increasing soil degradation and desertification.

90. Reason for soil degradation and
desertification
• Population Growth (the population of the region
is doubling in every 20 years)
• Deforestation (much of it caused by people
collecting firewood)
• Overgrazing: Nomadic herders keep cattles
• Rising temperatures (greater evaporation) and
reduced rainfall (droughts)
• Storms - the rainfall that does take place tends to
be in shorter more intense storms that can lead
to water erosion.

91. Problems of desertification
• Famine, shortage of food, water and other
resources
• Dust storms
• Conflict over diminishing resources

92. Solutions to desertification
• Build green wall – planting trees in deserts to
stop the spread of deserts.
• Reforestation (planting trees in deforested areas)
and afforestation (planting in new areas)
• Irrigation
• Population control to reduce pressure on
resources.
• Introduce GM (Genetically modified) crops that
can withstand dry, poor soil.

93. Tropical storms
• Hurricanes (typhoons or cyclones) are the
most violent storms on Earth.
• The scientific term for all these storms is
tropical cyclone.
• Only tropical cyclones that form over the
Atlantic Ocean or eastern Pacific Ocean are
called "hurricanes."

95. • Tropical cyclones are like giant engines that
use warm, moist air as fuel. That is why they
form only over warm ocean waters near the
equator.
• The warm, moist air over the ocean rises
upward from near the surface, causing an area
of lower air pressure below.

96. • Air from surrounding areas with higher air
pressure pushes in to the low pressure area.
Then that "new" air becomes warm and moist
and rises, too. As the warm air continues to
rise, the surrounding air swirls in to take its
place. As the warmed, moist air rises and
cools off, the water in the air forms clouds.
The whole system of clouds and wind spins
and grows, fed by the ocean's heat and water
evaporating from the surface.

97. • As the storm system rotates faster and faster,
an eye forms in the center. It is very calm and
clear in the eye, with very low air pressure.
Higher pressure air from above flows down
into the eye.

98. Tropical cyclone categories
Category
Wind
Speed
(mph)
Damage at
Landfall
Storm
Surge
(feet)
1 74-95 Minimal 4-5
2 96-110 Moderate 6-8
3 111-129 Extensive 9-12
4 130-156 Extreme 13-18
5
157 or
higher
Catastroph
ic
19+