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Introducing Introducing climateclimate

what is it?what is it?But before we look at the different But before we look at the different parts of climate, lets make sure we parts of climate, lets make sure we know the difference between it and know the difference between it and

weather first!weather first!

Have a tape measure of some sort for this lesson!

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Weather? Climate ? Which is which?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?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 summaryIn summary

Weather describes the daily conditions of a particular placewhereasclimate describes the general pattern over time

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Try these – weather or climate?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 atToday we will look at

Words to describe roughly the temperature and the precipitationWhat is it about a place that makes the climate of a place the way it is

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TemperatureTemperature

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 Wet stuff from the sky is precipitationprecipitation

So the following are types of precipitation

rainsnowhail or ice (this was in the air before it landed)

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PrecipitationPrecipitation

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!Lets practice!

July24th 2009 in Surrey, it was 36.50CBuntingford (Hertfordshire) recorded a minimum temperature of -12.3C on the 7th Jan this year. World Temperatures today:http://www.metoffice.gov.uk/education/teachers/latest_weather_data_world.htmlWhat is like and where?

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Lets practice!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 mmMadrid 470mmTabora , Tanzania 880mmLloro, 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 The world as you have never seen it before! From world mapperbefore! From world mapper

It says, ’Territory size shows the proportion of worldwide precipitation falling on land that falls there.’ What do you think that means?

Land area

http://www.worldmapper.org/index.html

Where is it wettest or

driest?

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What makes the climate different in What makes the climate different in different places?different places?

Its latitude: how far from the equator the place isIts altitude: how high it is above sea levelHow far from the sea it isIts 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 latitudeThe latitude

This affects temperature in 2 waysOne has to do with the tilt of the earth that changes with the seasonsThe 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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The height of the sunThe height of the sun Lets look at a diagramLets look at a diagram

same width ray, more

spread out –not so hot

same width ray, not

spread out at all, much

hotter

look how

much thicker the air

is

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Tilt of the Earth’s axis towards or away from the sun creates the seasons

Earth’s Seasons

North Pole

Earth

When the north pole tilts toward thesun, it gets more radiation – more warmth

during the summer

SUMMER (Northern Hemisphere)

South Pole

WINTER (Southern Hemisphere)

When the north pole tilts toward thesun, the south pole tilts away

So when it’s summer in the north, it’s winter in the south

Equator

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Tilt of the Earth’s axis towards or away from the sun creates the seasons

Earth’s Seasons

When the north pole tilts away from the sun, it gets less radiation –

So it’s colder during the winter

North Pole

Earth

WINTER (Northern Hemisphere)

South Pole

SUMMER (Southern Hemisphere)

When the north pole tilts away from thesun, the south pole tilts toward it…

When it’s winter in the north, it’s summer in the south

Equator

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In summaryIn summary

The higher the latitude (the further from the equator)

the more heat from the sun is absorbed by airthe more spread out the rays of the sun are so the bigger area has to share the heat that is leftthe greater the difference between summer and winter

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The altitudeThe 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)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 travelsthe 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 Why the sea is warmer in winter and cooler in summer than the landcooler in summer than the land

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.

Inland is solid and opaque so the top layer collects all

the heat and so it gets hotter.

Land near the sea is kept cooler than inland by the cooler sea

In Summer

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Why the sea is warmer in winter and Why the sea is warmer in winter and cooler in summer than the landcooler in summer than the land

Some warmth leaves the sea

The warmth from the

Summer goes deeper and so

is slower to cool down

Inland the surface heat is lost quickly,

and so the land cools down in

winter

Land near the sea is kept

warmer than inland by the warmer sea

In WinterMore warmth

leaves the land

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So in SummarySo 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 windThe prevailing wind

If the most usual wind comes a cross the sea, it tends to have more water vapour and hence bring rainIf 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 Where is it wetter in the UK?in the UK?

What pattern can you see?Do you know why this pattern exists?

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Evaporation of water from the ocean

Formation of Relief RainfallOccurs in the mountains on the west coast of Britain

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Evaporation of water from the ocean

Onshore moisture laden winds

Formation of Relief Rainfall

Occurs in the mountains on the west coast of Britain

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Mountains on the west coast of Britain forces the air to rise

Evaporation of water from the ocean

Onshore moisture laden winds

Air cools down

Formation of Relief Rainfall

Occurs in the mountains on the west coast of Britain

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Mountains on the west coast of Britain forces the air to rise

Water vapour Condenses to form

clouds

Evaporation of water from the ocean

Onshore moisture laden winds

Air cools down

Further cooling leads to precipitation

Formation of Relief Rainfall

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Air moving down the mountain, gets warmer and so reabsorbs any

remaining water vapour.

NO MORE RAIN

Water vapour Condenses to form clouds

Evaporation of water from the ocean

Onshore moisture laden winds

Air cools down

Formation of Relief Rainfall

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Relief RainfallRelief Rainfall

1 Air is forced to rise and cools by 1°C per 100m.2 As the water vapour in the air condenses, it forms

clouds and rains. 3 The air starts to descend and begins to warm up again.4 As air warms up, it can hold more water vapour - clouds

disappear and rain stops. This side is known as a RAINSHADOW.

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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Ocean currentsOcean currentsWhich parts of which continents are colder

than you would otherwise expect?

And which warmer?

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Homework Homework

Some fairly straightforward questions on what we have talked about in class today