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WeatherWeather

Last session!Last session!

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Last week …Last week …

We said thatThe British Isles has

a temperate Maritime climatea temperate Maritime climate

This meant that we neither hot nor cold, wet nor dryAndWe were by the sea so that had an effect as wellCan you remember what that effect was?

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Take a look at the map – they call ours Take a look at the map – they call ours Marine West Coast –not temperate Marine West Coast –not temperate

maritimemaritimeBut all the turquoise area is not

all the same!

Even the UK is not exactly

the same all over!

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As we said when ..As we said when ..

We looked at 3 factorsAverage January temperatureAverage July temperatureRainfall

We found that different parts of the country had different kinds of weatherAnd the British Isles could be roughly divided up into 4 regions. Can you remember how they were different?

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This is the map This is the map we usedwe used

What was the blue area like?The pink?The red?The green?

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But even within the red parts there But even within the red parts there are differencesare differences

Can you think which parts might be different from the general idea? Why?Which ones might be a bit cooler?A bit drier?A bit wetter?The warmest part?

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So from this I hope you see ..So from this I hope you see ..

That the world CAN be divided up into climate zonesBut not ALL the climate within that zone will be EXACTLY the same.There are reasons why some bits are warmer/colder or wetter/drier that average.We divided the UK into 4But even those 4 areas have variation because of local conditions.

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These smaller areas are called These smaller areas are called microclimatesmicroclimates

A microclimate is the distinctive climate of a small-scale area, such as a garden, park, valley or part of a city. The weather variables in a microclimate, such as temperature, rainfall, wind or humidity, are a bit different from the climatic conditions that you would expect.There are a number of these, but we are going to look at the more common ones.

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Upland regions Upland regions

Temperature usually falls with height at a rate of about 1 °C per 100 m.This means that in higher hills and mountains, the average temperatures can be so much lower that the winters are longer and summers much shorter. Higher ground also tends to be windier, which makes for harsher winter weather. Air forced to lift over hills cools and any water vapour that they hold condenses and turns into cloud.

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Upland regions Upland regions

This often means that hill tops receive more rain. What is this type of rainfall called? As the air blows over the hills and down the other side it warms and the rain drops turn back into water vapour. This is called a rain shadow. Why?Sunshine-facing slopes (south-facing in the Northern Hemisphere, north-facing in the Southern Hemisphere) are warmer than the opposite slopes.In Autumn, mist and fog form in the valley bottoms. Sometimes the hilltops are in the sunshine in the early morning, before the mist has evaporated.

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WoodlandsWoodlandsOn a hot summer’s day it is cooler in a wood that outside of it.

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Different trees make a Different trees make a difference!difference!

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Temperature in woodlandsWoodlands are normally cooler in summer and slightly warmer in winter.

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Coastal regionsCoastal regions

The coastal climate is influenced by both the land and sea between which the coast forms a boundary. The sea also takes a long time to heat up during the summer months and, conversely, a long time to cool down during the winter. This means that the coasts are usually milder than inland during the winter and cooler in the summerDuring autumn and winter, the coast tend to get more showers than inland, although during spring and summer they get less.On the other hand, a sea fog can be brought ashore and may persist for some time, while daytime heating causes fog to clear inland. Even when there is very little wind generally, during the summer, a breeze often comes from the sea (sea breeze) from late morning and from the land (land breeze) during the evening and night.

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Now this is an odd one that you may Now this is an odd one that you may not have thought of!not have thought of!

This is an urban microclimate – what does urban mean?Take a look at how different between urban and rural climates are:

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Towns are often described as Towns are often described as Urban heat islandsUrban heat islands

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Why does this happen?Why does this happen?

A number of things make this happen:The release of heat from industrial and domestic buildings;The absorption by concrete, brick and tarmac of heat during the day, and its release into the lower atmosphere at night;The reflection of solar radiation by glass buildings and windows. Pollutants from cars and heavy industry lead to the formation of cloud and smog, which can trap radiation (sun’s heat). Generally plants use up energy from the sun to transpire. But cities have fewer plants so this heat adds warming of the town’s atmosphere;There is little wind to disperse the heat and bring in cooler air from rural areas.

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But microclimates can be even But microclimates can be even smallersmaller

For instance, in my garden I have severalThere is a steep bank at one end of the house which reaches as high as the first storey - it is always in the shade and the wind would have difficulty getting in there. But while it does not get much direct rain, it is very wet as water runs off the top of the bank and also out of the soil as springs.

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There is another bank …There is another bank …

On the edge of the drive which is very exposed – it faces up a long valley from which a lot of wind and rain comes down.It does not get much sun though, so it tends to be cold – the spring flowers are always later coming out than on the grass oppositeThen there is the courtyard, which gets the sun but the walls protect it from the wind and it does not get all the rain either!

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We have LOTS of trees – under

some of those would

make a good

microclimate

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So this is to be your homeworkSo this is to be your homework

Find 2 or 3 microclimates in your garden – if you do not have one, is there a park nearby – or maybe a friends house?Decide why you think that this different from the rest of the area – and why that might be.Then try to get some evidence!If you have a thermometer, you could collect evidence that your microclimate id warmer or cooler – if you have not, there other things you can do!

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To make an anemometer you will need:a table-tennis ballsome fishing line or similar nylon corda protractor (or use the template on your homework sheet)Thread the table-tennis ball onto the fishing line or thick cotton or wool. Suspend this from the centre of the protractor so that it can swing freely. The fishing line should hang down the 90-degree line on the protractor. An indication of the wind speed will be given by the angle shown on the protractor when the instrument is held in the air. Wind speed readings can be taken at the same time as temperature measurements. (This is all on the sheet)

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Degrees to Km/hr

Force 1

Force 2

Force 3

Force 4

force 5

Force 6

Force 7

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

Degrees

Km

/hr

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Another anemometer!Another anemometer!

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Is there more rain in some places in Is there more rain in some places in the garden?the garden?

Get 3 or 4 containers that are EXACTLY the same – margarine pots, yoghurt pots, jars …?Why must they be exactly the same?Put one in each microclimatic zone and one somewhere that is not too shaded or exposed or too much anything.Then hope for rain over the next day or 2!If it does rain, collect them all in and used a measuring jug to see which has collected the most and which the least!

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This homework This homework does not have to does not have to be in on Fridaybe in on Friday

As long as I get it before As long as I get it before the end of half term, that the end of half term, that

will be fine!will be fine!