Transcript Introducing climate what is it?

Introducing climate
what is it?
But before we look at the different
parts of climate, lets make sure we know
the difference between it and weather
first!
Have a tape measure of some sort for this
lesson!
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Weather? Climate ? Which is which?
WEATHER describes conditions in the
atmosphere at any time or short period of
time.
Weather conditions can change suddenly.
Today may be warm and sunny, tomorrow
may be cool and cloudy.
Weather conditions include rain, snow,
sleet, hail, fog, mist, sunshine, wind,
temperature and thunderstorms.
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Weather? Climate ? Which is which?
CLIMATE describes surface and atmospheric
conditions over a longer time period or over a
large geographical area.
The climate of an area is concerned with the
AVERAGE weather conditions which are taken
over a year or more.
Climate changes slowly, usually over decades,
centuries and thousands of years.
The Earth has many climate regions.
Britain is in the Temperate Climate Belt, with
winters that are not too cold and summers that
are not too hot.
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In summary
Weather describes the daily conditions of
a particular place
whereas
climate describes the general pattern
over time
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Try these – weather or climate?
“I think we should move to France where it is
warmer.”
“My washing will never dry today.”
“December is wet and cold.”
“Where should we go for our skiing holiday this
year?”
“There is too much fog for the plane to land.”
“Bananas grow in Jamaica because it is hot.”
“Sports Day is cancelled, it is raining too much.”
“Take your coat to school today.”
“It’s October, it’ll be getting cold soon, I’d
better put the heating on.”
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Today we will look at
Words to describe roughly the
temperature and the precipitation
What is it about a place that makes the
climate of a place the way it is
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Temperature
To be able to
identify a climate you
need to be able to
describe the
temperature of the
hottest and coldest
months and the
temperature range.
The describing words
for temperature are
shown on the
thermometer on the
left.
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Wet stuff from the sky is precipitation
So the following are types of
precipitation
rain
snow
hail or
ice (this was in the air before it landed)
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Precipitation
You also need to
be able to
describe the total
amount of annual
rainfall - that is
how many
millimetres fall in
a year. The
pattern of rainfall
is also important.
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Lets practice!
July24th 2009 in Surrey, it was
36.50C
Buntingford (Hertfordshire)
recorded a minimum
temperature of -12.3C on the
7th Jan this year.
World Temperatures today:
http://www.metoffice.gov.uk/e
ducation/teachers/latest_weat
her_data_world.html
What is like and where?
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Lets practice!
Annual Rainfall
Wigboro Wick Farm, St Osyth in
Essex has 500mm of precipitation
each year
Crib Goch in Snowdonia, Wales has
4470 millimetres a year
(oops – what shall we call more than
2000mm?)
Rome 760 mm
Madrid 470mm
Tabora , Tanzania 880mm
Lloro, Colombia (on the edges of the
Amazon 13.3 meters
[I know all the others are in mm but
this would be 13,300 mm – a bit hard
to image – how tall are you? How
many of you would need to stand on
each other’s head for the top one to
breath?]
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The world as you have never seen it before!
From world mapper
Where is it
wettest or
driest?
Land
area
http://www.worldmapper.org/index.html
It says, ’Territory size shows the proportion of
worldwide precipitation falling on land that falls
there.’ What do you think that means?
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What makes the climate different in
different places?
Its latitude: how far from the equator the place
is
Its altitude: how high it is above sea level
How far from the sea it is
Its prevailing winds (the direction from which
the wind comes most often)
Ocean currents – these may bring warm water to
the colder areas, warming the coastal parts but
also bringing rain. Cold currents from the artic
regions cool the coasts
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The latitude
This affects temperature in 2 ways
One has to do with the tilt of the earth
that changes with the seasons
The other has to do with the height of
the sun in the sky, and so how much each
patch of earth is warmed
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same width
ray, not spread
out at all, much
hotter
The height of the sun
Lets look at a diagram
same width
ray, more
spread out –
not so hot
look how
much
thicker
the air
is
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Earth’s Seasons
Tilt of the Earth’s axis towards or away from the sun creates the seasons
When the north pole tilts toward the
sun, it gets more radiation – more warmth
during the summer
When the north pole tilts toward the
sun, the south pole tilts away
So when it’s summer in the north,
it’s winter in the south
SUMMER (Northern Hemisphere)
WINTER (Southern Hemisphere)
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Earth’s Seasons
Tilt of the Earth’s axis towards or away from the sun creates the seasons
When the north pole tilts away
from the sun, it gets less radiation –
So it’s colder during the winter
When the north pole tilts away from the
sun, the south pole tilts toward it…
When it’s winter in the north,
it’s summer in the south
WINTER (Northern Hemisphere)
SUMMER (Southern Hemisphere)
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In summary
The higher the latitude (the further from
the equator)
the more heat from the sun is absorbed by air
the more spread out the rays of the sun are
so the bigger area has to share the heat that
is left
the greater the difference between summer
and winter
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The altitude
The higher a place is above sea level, the
colder it gets.
In Scotland, Braemar (339m) has an
annual average temperature of 6.4°C,
While average at Ben Nevis (1344m) is
-0.3°C.
On Everest(8,848m), the average
temperature is -40°C compared to an
average of 15°C at sea level
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Distance from the sea ( or continentality)
Places near the ocean, tend to have more
rain than those in land
at least some of the wind will come from
across the sea, picking up water vapour as it
travels
the land next to the sea is higher and
therefore relief rain will tend to happen
Places near the sea will tend to have
warmer winters but cooler summers that
those in land. Why?
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Why the sea is warmer in winter and cooler
in summer than the land
In Summer
Warmer
Summer air
Water is a
liquid and is
transparent.
So the radiant
heat is spread
out more – to
a great depth.
So it does not
heat up so
much.
Land near the sea
is kept cooler
than inland by the
cooler sea
Inland is solid and
opaque so the top
layer collects all the
heat and so it gets
hotter.
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Why the sea is warmer in winter and cooler
in summer than the land
In Winter
Some warmth
leaves the sea
The warmth
from the
Summer goes
deeper and so
is slower to
cool down
Land near the
sea is kept
warmer than
inland by the
warmer sea
More warmth
leaves the land
Inland the surface
heat is lost quickly,
and so the land
cools down in
winter
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So in Summary
In Summer inland areas are warmer than
the coast or the land nearby.
But in Winter inland areas are colder than
the coast and land near it
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The prevailing wind
If the most usual wind comes a cross the
sea, it tends to have more water vapour
and hence bring rain
If the most usual wind comes across the
land, it is likely to be dry and so not bring
much rainfall
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The prevailing wind in the UK is from the SW across the Atlantic –
wet!
But if you are in New York, the prevailing wind is NW across the US
mainland – dry
Look at the Sahara -they come from a long stretch of land from Asia
– that explains a thing or 2!
But it is not just wet winds that make the coastal regions wetter
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Where is it wetter
in the UK?
What pattern
can you see?
Do you know why
this pattern
exists?
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Formation of Relief Rainfall
Occurs in the mountains on the west coast of Britain
Evaporation
of water from
the ocean
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Formation of Relief Rainfall
Occurs in the
mountains on the
west coast of
Britain
Onshore
moisture laden
winds
Evaporation
of water from
the ocean
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Formation of Relief Rainfall
Occurs in the mountains
on the west coast of
Britain
Onshore
moisture laden
winds
Air cools
down
Mountains on the west
coast of Britain forces
the air to rise
Evaporation
of water from
the ocean
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Formation of Relief Rainfall
Onshore
moisture
laden winds
Air cools
down
Water vapour
Condenses to form
clouds
Further cooling
leads to
precipitation
Mountains on the west
coast of Britain forces
the air to rise
Evaporation
of water from
the ocean
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Formation of Relief Rainfall
Water vapour
Condenses to
form clouds
Onshore
moisture laden
winds
Evaporation
of water from
the ocean
Air cools
down
Air moving down the
mountain, gets warmer
and so reabsorbs any
remaining water
vapour.
NO MORE RAIN
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Relief Rainfall
Relief rain is formed when
air is forced to cool as it
rises over relief (height)
features in the landscape
(hills or mountains).
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Air is forced to rise and cools by 1°C per 100m.
As the water vapour in the air condenses, it forms clouds and
rains.
The air starts to descend and begins to warm up again.
As air warms up, it can hold more water vapour - clouds
disappear and rain stops. This side is known as a
RAINSHADOW.
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Which parts of which
continents are colder than
you would otherwise
expect?
Ocean currents
And which
warmer?
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Homework
Some fairly straightforward questions
on what we have talked about in class
today
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