Transcript The Natural World – Revision Notes

The Natural World –
Revision Notes
What Is the Natural World?
• This unit comprises three major
concept areas. Weather,
Climate and Ecosystems
• Weather is the day to day
changes in the state of our
atmosphere and consists of
changes in pressure,
temperature, humidity and wind.
• Climate is the average weather
over a long period of time (e.g.
over 30 years)
• An ecosystem is a collection of
plants and animals that live in
the same geographic region
adapted to certain climate
characteristics (e.g. Tropical
Rainforests, Grasslands,
Temperate forests)
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Air
Masses
and
the
UK
Air Masses are large bodies
of air that have relatively
uniform temperature and
humidity characteristics.
They pick up these
characteristics from their
source region (where they
come from) and the land or
sea they travel over when
they travel to the UK.
Polar air masses bring cold
temperatures to the UK
Tropical air masses bring
warmer weather to the UK
Continental air masses pass
over land hence are dry
Maritime air masses pass
over water hence bring moist
air to the UK
What weather would the five
air masses on the map
opposite bring to the UK?
Relief Rainfall
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Relief rainfall occurs where moist air is
forced to rise over a physical barrier such
as a mountain range.
Warm air is carried to the West coast of
Britain by our prevailing (dominant)
winds, the westerlies.
On the diagram, this air encounters the
high land at the Lake District and the
Pennines and it is forced to rise above
this barrier.
Second, as it rises, the warm air cools
with height at a rate of 1°C per 100m. As
the air cools water vapour condenses to
form clouds and eventually it rains over
Britain's highland areas.
As the air descends to the East coast of
Britain it warms slightly and there is less
rainfall.
This results in a rainshadow on Britain’s
east coast
It is for this reason that the West coast of
Britain is wetter than the East, Blackpool
receives 950mm of rainfall per year, The
Pennines 2000mm+, and Newcastle
700mm.
Convectional rainfall
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This type of rainfall occurs in
summer months for the UK and
brings heavy rainfall and violent
thunderstorms to our country.
Short wave radiation arrives at the
earth’s surface and is converted to
long wave HEAT energy.
This heat energy heats the air
above it.
The now warmed air has more
energy and rises through our
atmosphere and away from the
Earth’s surface in THERMALS
which rise as fast as 25m/second.
As it rises, the warm air cools with
height at a rate of 1°C per 100m
As the air cools water vapour
condenses to form
CUMULONIMBUS clouds and
eventually it rains over the UK.
These events occur mainly in
summer and in the south east of the
country.
Depressions
• These storms affect the UK
throughout the year and bring wet
and windy weather to the UK.
• Warm air (™) migrating north
from the tropics meets cold
dense air (PM) migrating South
from the Polar region.
• The warm air is undercut by the
advancing cold air and because it
has more energy and is less
dense is forced to rise upwards at
a COLD FRONT
• Ahead of this, warm air advances
into cold air and is also forced to
rise above this denser cold air at
a WARM FRONT.
• At both fronts air is rising so
cooling and condensation take
place which eventually results in
rain AT BOTH FRONTS.
The Weather in a Depression
• Here you can
see the weather
a depression
brings to the
UK. Note that
this is a cross
section through
the depression.
As this storm
passes from the
West of the UK
to the East what
changes would
occur in our
weather?
Anticyclones
• Anticyclones are areas of HIGH PRESSURE where
air is descending. Air is sinking to the earth’s
surface in an anticyclone, so condensation does not
take place and therefore skies are clear. Winds are
very light in an anticyclone and ISOBARS (lines
joining areas of equal pressure on a weather map)
are far apart.
• In WINTER anticyclones bring very cold settled
weather to the UK.
• In SUMMER anticyclones bring very hot settled
weather to the UK, as witnessed in the heat wave of
2003.
Interpreting Synoptic Charts
(weather maps)
What is this feature
here?
What is this
weather feature
here?
What would the
weather be like
here? Why?
What would the
weather be like
here? Why?
What is happening
to the air molecules
here?
What is happening
to the air
molecules here?
What will this weather
system eventually bring
to the UK? Where do it’s
air masses come from?
What are these lines
on the map?
What can they tell you
about the weather on
this map?
What symbols
are there on the
map? What do
they mean?
Maritime and Continental Climates
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20
100
15
80
10
60
5
40
0
20
-5
0
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Temperature (degrees Celcius)
Precipitation mm)
Average Climate in Plymouth
(Maritime)
Precipitation (mm)
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Temperature (Degrees C)
-10
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
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Month
Average Climate in Kiev,
Continental Interior
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25
90
Precipitation (mm)
15
70
60
10
50
5
40
30
0
20
-5
10
0
-10
Jan
Feb
Mar
Apr
May
Jun
Jul
Month
Aug
Sep
Oct
Nov
Dec
Temperature (degrees Celcius)
20
80
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Precipitation (mm)
Temperature (Degrees C)
Kiev and Plymouth are both on the same line
of Latitude (50°N) so should have very similar
climates.
Looking at the graphs opposite you can see
that Kiev is warmer in summer and colder in
winter than Plymouth.
In addition, Plymouth receives more rainfall
that Kiev, and Kiev has a summer rainy season
in contrast to a winter rainy season in
Plymouth. This proves they have different
climates.
The reason for the different rainfall is that
Plymouth is surrounded by ocean water so has
more available moisture, hence it is wetter
than Kiev.
Winter Depressions bring Plymouth most of its
rainfall, in contrast to convections ate Kiev in
the summer, hence the different rainy seasons.
Temperature is different because Plymouth is
surrounded be water and Kiev is in the middle
of a continent, surrounded by rock. Water
retains its heat in winter warming coastal
temperatures in Plymouth. A warm ocean
current called the North Atlantic Drift , also
warming Plymouth in Winter. Kiev is
surrounded by rock which loses its heat in
winter quickly, causing Kiev to be cold. In
summer the rock heats quickly, giving Kiev
high summer temperatures.
Global Distribution of Forest Ecosystems
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Tropical forests are found between the
Tropics of Cancer and the tropic of
Capricorn. Within these two lines of
Latitude are found the Amazon forest in
South America, Western central Africa,
Indonesia and Northern Australia. They
are exposed to average temperatures of
30°C which vary little and it rains a lot
(over 2000mm per year).
Taiga (temperate coniferous forests) are
found in a wide band between 50°N and
the Arctic circle. They stretch across
Canada, northern Europe (Scandinavia)
and the Russian area of Siberia. There
are no coniferous forests in the Southern
hemisphere because of the lack of land
at that latitude. These forests are
adapted to cold temperatures.
Temperate Deciduous forests are found
between 30°N and 60°N of the Equator in
Europe, Asia and North America. They
are adapted to areas with a small
temperature range, and reliable rainfall.
They do not occur in continental areas of
Europe because it gets too cold in
winter.
Adaptations of Taiga forest to
their environment
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These forests contain species such as Douglas Fir
and Scots pine, and can grow to heights in excess of
30m. Each forest contains only one type of tree and
has little vegetation on the forest floor because it is
dark and the soil is acidic.
Trees are evergreen so can photosynthesise when
temperatures rise above 3°C so maximise available
sunlight.
Leaves are needle shaped and therefore have a small
surface area and are waxy. This reduces moisture
lost by transpiration, important as these areas receive
little moisture (less than 500mm)
The conical shape of trees give them stability in high
winds.
Bendy trunks also guard against high winds.
Branches slope downwards so they do not snap
under the weight of snow.
Seeds are protected against cold in cones.
Trees have wide spreading roots in shallow soils.
Soils are shallow because of slow rates of decay.
Adaptations of Tropical
rainforests to their environment
• Examples of adaptations of plants to the climate.
• Leaves have drip tips to allow the vast quantities of
water to run off without damaging the leaf.
• Trees grow tall to reach the sunlight.
• Lianas and vines hug trees to take advantage of
nutrients and sunlight and maximise use of space.
• Trees have wide roots and thick trunks to support
their size – called buttress roots.
• Mosses and ferns grow on the forest floor and can
live on low levels of sunlight.
Threats and solutions to tropical
rainforests
This is Papua New Guinea, it
is covered in Tropical
rainforest. It has over 9000
species of plants, 250
species of mammals and
700 species of birds. It has
a really rich biodiversity
but this ecosystem is
threatened. The
population are very poor,
there are low levels of
literacy (70%) and only 1
doctor for every 12,500
people. The government
has allowed widespread
use and exploitation of the
forest in the past.
How the forest is being
exploited.
How the forest is
being sustainably
developed
How the rainforest is
being conserved
Sissano Lagoon – This
been cleared of rainforest
so that a company can
grow oil palm trees. The
oil palm is used for
soaps, greases and
detergents. This has led
to soil erosion and the
sediment has run from
the soil, into rivers and
into a local lagoon, killing
the coral there.
Kikori Basin –
Chevron, an American
oil company, drilled for
oil in Kikori and
shipped the oil out of
the area using
pipelines. All of this
involved cutting down
trees. They tried to
make the project more
sustainable by
encouraging local
people to use the
forest for agriculture,
fish farming,
ecotourism and to
develop cottage
industries.
The Crater Mountain
wildlife Management area
was set up in the 1990s
and conserves 2600KM2
of rainforest. This area
has developed
ecotourism and has
limited the impacts of
logging and mining
Threats and solutions to tropical
rainforests
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Causes of deforestation
Cattle Ranching -where large tracts of land are cut down
to make way for low quality grazing land for cattle. The
land loses its nutrients very quickly and becomes infertile.
Lumbering/Logging – where the rainforest is cut down to
collect high quality hard woods such as Mahogany and
teak. The lumberjacks have to clear large areas of forest
to access these valuable trees, which are few and far
between.
Mining – In the Carajas region of the forest vast quantities
of Iron can be found and huge mines have been
developed to exploit this valuable resource at the expense
of the trees. The rail links needed to transport the iron
have also resulted in deforestation.
Effects of deforestation
Increased flooding because trees do not catch the rain
any more.
Loss of habitat for the millions of species that live in the
forest resulting in extinctions.
Alters the water cycle.
When the trees are burnt down they emit Carbon Dioxide
which can contribute to global warming.
Trees emit Oxygen, less trees means less Oxygen for us
to breath.
Medical plants and cures are lost.
Indigenous tribes of Amerindians are moved on.
Rare plant and animal species are lost.
Soil erosion is increased.
Solutions to rainforest
destruction
• Solutions/ Alternatives
– Shifting cultivation – farmers cut down and burn the
vegetation in a small area of land and farm it. When the
lands nutrients are used up the farmers move on to another
plot of land. This allows the initial farm plot time to recover
and for the natural vegetation to grow again.
– Use Helicopters to lift logs out of forest – less damage
caused.
– Encourage tree planting programmes
– Sustainable farming – planting crops between the forest
trees and collecting the forests natural resources through
rubber tapping.
– Switch to fast growing soft wood trees such as pine.