Transcript Australia*s climate and vegetation

Australia’s climate and
vegetation
Climate is the pattern of weather that is expected in a
particular place, based on the experience of the previous
30 years. It is not just the ‘average weather’ as it takes
into account the extremes that can occur. Patterns of
climate and vegetation are closely related because climate
is the main factor that determines where plants can grow.
Australia’s pattern of
climate
• Australia has a wide range of climates due to its
location and extent. About 40 per cent of the
continent lies within the tropics—the zone
between the Equator and the Tropic of
Capricorn—where it is warm all year round and
there are only two seasons—wet and dry. The
remainder of the country lies in the temperate
zone and experiences four seasons—spring,
summer, autumn and winter—each with its own
distinctive weather patterns.
Factors influencing Australia’s climate
One of the most distinctive features of the Australian climate is its variability.
There are a range of factors that influence climate and are responsible for
the changes that occur from region to region and from year to year.
• Latitude—The Earth receives more of the Sun’s energy at the Equator than at
the poles so temperatures are highest at the Equator and decrease as
latitude increases.
• Distance from the coast—The sea has a moderating effect so temperature
ranges are less at the coast than inland. Onshore winds bring higher
precipitation to coastal areas.
• Ocean currents—Currents from nearer the poles bring cooler conditions and
those from nearer the Equator bring warmer conditions.
• Direction of prevailing winds—Winds from nearer the Equator are warmer
than those from nearer the poles. Winds from over the ocean bring
precipitation and those from inland are dry.
• Relief—Temperature decreases with height. Moist air that is
forced to rise by mountains cools, and the water vapour
condenses, producing increased cloud cover and
precipitation. Highland areas are cooler and wetter than
lowland areas.
• Pressure systems—High pressure associated with sinking air
brings dry settled weather. Low pressure caused by rising air
brings unsettled weather. Australia is dominated by high
pressure with low pressure in the north during summer and in
the south during winter.
• El Niño—The normal circulation pattern in the Pacific Ocean
brings rain to Australia. In an El Niño year the circulation
reverses and South America receives the rain while Australia
remains dry.
Climate graphs
Climate graphs show the average temperature and rainfall
for a given place over a 12-month period. They are
used by geographers to study spatial patterns of
climate and the relationships between temperature
and rainfall. Each graph is composed of a column graph
showing the precipitation and either one line graph
showing the average temperature or two line graphs,
one showing the average maximum temperature and
the other showing the average minimum temperature.
Climate graph
Activity
•
Go to the site below and complete the Activities
•
http://www.bom.gov.au
Activities
1. Go to climate information and then Climate data online
a) Choose either temp or rainfall
b) Choose an area
c) Choose a station
d) Click get data
e) On the spreadsheet go to the little chart icon in the last column of the spread sheet
f) Use this information to create a climate graph
Pressure Patterns
Standard Symbols
Pressure patterns
• http://www.seabreeze.com.au/info/wind.asp
• Cut out pictures for worksheet and paste
them in your book and then using the website
above describe each pressure system
Vegetation