y7ge u2_b weather types sep 23

7/31/2019 Y7Ge U2_B Weather Types Sep 23

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Weather and Climate 1

Whether itis climateor not?


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Today we will look at

1. What makes weather?2. How do we measure weather?

3. Why do we need forecasts?

4. Are the forecasts any good? (thatshomework)


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What is the weather?

Weather is the condition of the

air around us over a short periodof time (from day to day)


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The elements of weather

Temperature (the amount of heat)Precipitation (water rain, sleet, hail,snow)

Wind speedWind direction

Clouds

Air pressureVisibility (How far can you see?)


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Temperature

This is a measure ofhow hot or cold it is.We can tell this bylooking at the

clothes that peoplewear.


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Precipitation

Water in the air fallsto the ground in oneof several formsRain

SnowSleetHailBut also ice and fog


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Wind Speed

This tells us howstrong the wind is.We can get a goodideas of this bylooking at smoke

and trees.


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Wind direction

This is thedirection fromwhich the windblows it is

measured by awind vane


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Cloud Type

Clouds come in manyshapes, sizes andheights more aboutthat next week


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Cloud Cover

This is the amount ofthe sky covered bycloud. It ismeasured in eighths

Clear sky

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8/8 (Total cover)


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Visibility

This is the distancethat can be seen. Itis measured inmetres.


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Measuring Weather

Why do we measure the weather?Weather can be described using terms such as wet orfine, warm or cold, windy or calm, so why is there aneed to measure the weather?

For most people, a description of the weather isadequate but for many businesses more detailed andaccurate measurements are required.The science of studying weather is called meteorology.Weather scientists or meteorologists measure

temperature, rainfall, pressure, humidity, sunshine andcloudiness and they make predictions and forecastsabout what the weather will do in the future.This is important for giving people advance notice ofsevere weather such as floods and hurricanes or evenCan I go out without my raincoat tomorrow?

Who else mightfind a forecast

useful?


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Measuring temperatureThe hotness or coldness of a substance is called its

temperature and is measured with a thermometer. Theordinary thermometer consists of a hollow glass bulbattached to a narrow stem with a thread-like bore.The bulb is filled with liquid, If it is silver it is mercury

If it is red it is alcoholThe liquid in the tube expands when the temperaturerises and contracts when the temperature falls. Theamount of expansion and contraction is measured by anumbered scale.Whilst thermometers are really measuring their owntemperature, they are used to measure thetemperature of the surrounding air.To make sure that the temperature of the surroundingair is the same as the thermometer, it must be shadedfrom sunlight and be exposed to adequate ventilation.

These conditions are provided by a Stevenson screen.


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A Stevenson screen

Why do we needone of these?

Why does it

have legs?

Why is it painted

white?

Why has it got such a large

roof?

What are the

little gaps in

the side for?

(louvers)


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Measuring temperature

Most temperature scales today areexpressed in degrees Celsius (C),although you will sometime see

Fahrenheit (F) in use.The Celsius scale is fixed by two points,the freezing and boiling point of water,

which at sea level are 0C and 100Crespectively.

The scale is then divided into 100 units.


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Measuring TemperatureThis is a maximum-minimumthermometer.This type of thermometermeasures both the highest(maximum) and lowest (minimum)

temperature over a period of time,usually one day (24 hours).Recording temperature with amaximum-minimum thermometerThere are two markers, one forthe maximum temperature and onefor the minimum. The mercury inthe tube pushes the markers astemperatures go up or down.


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Measuring Temperature

The temperature tends to be highest aroundthe middle of the day, when the sun is at itshottest even if you cannot see it because itis cloudy

The temperature is coldest during the nightSo if you leave a maxi-min thermometer for 24hours you will get the maximum and theminimum and be able to find the daily range

(the difference between the 2)The difference between the daily maximumand the daily minimum temperature is thediurnal range.


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Looking at the first 2 rows on theWS

What does a thermometer do?How does it work?

What does a maxi-min thermometer tellyou?What is diurnal range?

What does a Stevenson screen do?

How does it work?


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Wind speedWind is moving air.

Wind can be measured by its speedand the direction from which it hascome.The speed of the wind can bemeasured using a weather instrumentcalled an anemometer.The speed can be recorded in manydifferent units, including forexample: miles per hour;

kilometres per hour; metres per second; knots; the Beaufort Scale (we will learn about

this one next week)

This one hasa weather

vane on itunderneath.What doesthat tell

you?


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Wind directionThe direction of the wind is expressed as thepoint on the compass from where the wind isblowing.If a wind is blowing from the south, it istravelling northwards but is called a southerly

wind.Wind direction can be measured in manydifferent ways; using a weather vane or simplyholding a light object such as a flag or ribbon.

On your sheet, write down what they aresmelling!!http://www.bbc.co.uk/schools/whatisweather/aboutweather/winddir.shtml
http://www.bbc.co.uk/schools/whatisweather/aboutweather/winddir.shtmlhttp://www.bbc.co.uk/schools/whatisweather/aboutweather/winddir.shtmlhttp://www.bbc.co.uk/schools/whatisweather/aboutweather/winddir.shtmlhttp://www.bbc.co.uk/schools/whatisweather/aboutweather/winddir.shtml


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Wind direction

Knowledge of wind direction is importantfor many people and activities.For example aircraft need to take offfrom the end of the runway which is

going into the wind for extra lift attake-offWind direction is of course very

important for leisure activities such asyachting.Can you think of anything else whereknowing the wind direction is important


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For the WS

What is an anemometer for?How does it work?

What is a weather vane for?

How does it work?


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Air pressureAn instrument called abarometer is used tomeasure the pressure ofair.Although air is very light,because the atmosphere is

so thick (many kilometres inaltitude above the Earth'ssurface), air exerts a forceor pressure.When air is cooled it sinks

towards the ground, thepressure increases and ahigh pressure is measured.When the air warms up itrises, the pressure isreduced and low pressure ismeasured.

This is what goes oninside a barometer


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Air pressure

Why do we need to knowabout pressure?

High pressure gives us

clear skies which means itis hot in the summer andcold in the winter

Low pressure gives uscloudy skies and rain. Wehave lots of low pressureover the summer in the UK!


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For the WS

What is a barometer for?How does it work?

What is weather like if the pressure is

high in summer?What is the weather like if the pressureis low?


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Measuring liquid precipitation

What varieties of precipitation arethere?

Which types are NOT liquid?

Why do you think that if we measuredthis one, that we might not use the sameinstrument as the liquid one?

Thi i th i d b th


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This is the rain gauge used by theMet Office

Why do you

think the actualfunnel is inside a

copper cylinder

not a the top?

Why is the bottle

that stores the water

underground?

How does the

measuring gauge

on the right work?


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For the WS

What is a rain gauge for?What kind of precipitation does it notcollect?


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Weather is important to us

Things that are affected by weather farming sport

transport the amount of energy we use

work

tourism


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So we need weather forecasts

Information iscollected by weather stations

http://www.weatherst

ations.co.uk/aws_map.htm

Often schools havethem
http://www.weatherstations.co.uk/aws_map.htmhttp://www.weatherstations.co.uk/aws_map.htmhttp://www.weatherstations.co.uk/aws_map.htmhttp://www.weatherstations.co.uk/aws_map.htmhttp://www.weatherstations.co.uk/aws_map.htmhttp://www.weatherstations.co.uk/aws_map.htm


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So we need weather forecastsInformation is alsocollected byBy shipsAircraft

Satellitesand then themeteorologists usethe information they

have to predict theweather over thenext few days


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Weather from the met office

Fridays map fromhttp://www.met-office.gov.uk/weather/europe/uk/uk.html
http://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.htmlhttp://www.met-office.gov.uk/weather/europe/uk/uk.html


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This was the windmap. The numbersmeasure in miles perhour with direction it

is blowing tohttp://www.met-office.gov.uk/weather/europe/uk/uk.html


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This was theTemperature map.The numbersmeasure in degrees

centigradehttp://www.met-office.gov.uk/weather/europe/uk/uk.html


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And BBC weatherFromhttp://www.bbc.co.uk/weat

her/ukweather/index.shtml

It used to show it all onbut now they just showwhere the cloud is!!
http://www.bbc.co.uk/weather/ukweather/index.shtmlhttp://www.bbc.co.uk/weather/ukweather/index.shtmlhttp://www.bbc.co.uk/weather/ukweather/index.shtmlhttp://www.bbc.co.uk/weather/ukweather/index.shtmlhttp://www.bbc.co.uk/weather/ukweather/index.shtmlhttp://www.bbc.co.uk/weather/ukweather/index.shtml


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And weather onlineFrom

http://www.weatheronline.co.uk

Does show it allexcept the windspeed anddirection!!


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Symbols aredifferent butonce you get theidea

So what is theweathersupposed to belike in each of

these places?


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Homework

Go to (hopefully now!)http://www.weatheronline.co.uk/

Click either UK oryour continent

If it is the UK, clickon your region

Do not go moredetailed than that

If a continent, pickwhich part, then pickyour country
http://www.weatheronline.co.uk/http://www.weatheronline.co.uk/http://www.weatheronline.co.uk/http://www.weatheronline.co.uk/


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I am doing South Africa for Toby

I clicked on AfricaSouthern Africa

South Africa and Isaw this

But I dont wanttoday I wantWednesday toSunday

The other days aretabs above the maps

You do need to label the days it does not


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You do need to label the days it does notcome up with it if you use right click and

copy image

Now you have got your weather


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Now you have got your weatherforecast

Look out each day how good was theforecast?

If you have a thermometer, do use it and

add that information in!If you havent, not to worry.

Having put your pictures into the table

Record the weather you had in themiddle column

Now you have got your weather


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Now you have got your weatherforecast

In the last column, comment on whether theweather forecast was completely rubbish,pretty good or spot on

Remember to give your opinion and then add a

because. Remember what we said aboutcomparing things

For example:

I thought the weather forecast wascompletely wrong. This is because the forecastsaid it would snow when really there wasmostly sunshine with a few clouds.

y7ge u2_b weather types sep 23

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