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What is weather?
It is the state of the atmosphere at a
specific time and place.
It is the one thing that you can talk to
anybody about if you don’t know what to talk
about!
Auckland’s weather!
NZ Weather
Describe the weather map below.
• www.metservice.co.nz
What the weather map shows.
Isobars are lines joining places of equal
atmospheric pressure.Warm and cold fronts.
High pressure (1033hp) = anticyclone. Descending air
means no clouds, clear skies, low wind speeds in an
anticlockwise direction in the southern hemisphere.
Low pressure(976hp) = depression or cyclone.
Rising air means clouds, rain, strong winds in a
clockwise direction in the southern hemisphere.
( extreme low pressure = tropical cyclone/hurricane)
The closer the isobars are together, the stronger the wind speeds.
Air Masses
• A large body of air that
has properties similar to
the part of the Earth’s
surface over which it
develops.
Air masses may have low pressure or high pressure
A LOW PRESSURE SYSTEM or DEPRESSION
The lines on the map with red half circles mark a warm
front and the one with blue triangular blobs mark a cold
front. A front is a boundary between two air masses of different density,
moisture, or temperature
Depressions form when a warm air mass meets a
cooler air mass.The warm air is forced to rise over
the cold air and each front is marked by a band of
frontal rain.
6. Air masses and fronts
A Low Pressure System or Depression
Frontal Rain can be heavy!
There are 3 Types of Rainfall
• Draw the diagrams below and label them.
Why does Rain fall from Clouds?
Inside a cloud, there is a continuous supply of water
vapour causing growth of cloud droplets. The cloud
droplets may then fall due to their size and weight.
Larger cloud droplets falling at a faster rate collide
with the smaller droplets falling at a slower rate and
thus grow larger in size. This process is called
coalescence. As this coalescence process continues
inside a cloud, cloud droplets grow larger and larger
until they are too heavy to remain in the cloud and
thus fall toward the surface as rain.
Types of Precipitation
Rain
Sleet
Snow
Hail
Clouds
Types of clouds
Cumulo-nimbus Sb Can cause lightning, thunder, hail, strong
rains, strong winds, and tornadoes
Cirro-stratus Cs Thin, wispy, appears in sheets.
Cirrus Ci Thin, wispy, filamentous, or curly
Cirro-cumulus Cc Small, puffy, patchy and/or with a wavelike
appearance
Alto-cumulus Ac Medium-sized puffy, patchy, scattered clouds
- often in linear bands
Alto-stratus As Thin, uniform
Strato-cumulus Sc Broad and flat on the bottom, puffy on top
Cumulus Cu Puffy and piled up.
Stratus St Uniform, flat, thick to thin layered clouds will illdefined edges
Nimbo-stratus Ns Uniform, dark, flat, low, featureless clouds
that produce precipitation
Local Weather
Different rates of heating of land and water
•
•
•
•
•
Warm air over land rises
Sea Breeze moves inland
Cumuli develop aloft and move seaward
Upper level return land breeze
Cool air aloft sinks over water
•
Sea Breeze (meso-cold) Front
CLIMATE is a generalisation about
our weather.
Weather is what is happening in the atmosphere above us now.
Today it is _________________________________
Climate is a generalisation about what it is mostly like at this
time of the year. In winter in Auckland it is usually cold and
wet.
Weather patterns in the world are caused by the unequal
heating of the sun, due to the rotation of the earth around
the sun and the spinning of the earth once around on its axis
in 24 hrs, resultant pressure zones and wind patterns.
1 and 2
World wind patterns
3
4
As air moves from high to low pressure in the northern hemisphere, it is
deflected to the right by the Coriolis force. In the southern hemisphere, air
moving from high to low pressure is deflected to the left by the Coriolis
forceforce.
Task: Choose one example of an extreme
weather event.
1.Knowledge
Describe what happened, when it happened
and where it happened and the impacts.
2Comprehension Explain why it happened/what caused it.
3.Application
Draw a sequence of events diagram,
including impacts.
4.Analysis
Compare your extreme weather event with
one somewhere else in the world.
5.Synthesis
Decide which extreme weather event of the
type you have studied was the most
significant and justify your decision.
What would happen if humans could control
the weather?
6.Evaluation