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Weather and ClimateLesson 2
How do we measure the weather?
Wednesday 18th January 2012
Lesson Objectives
• To know the names of weather instruments
• To understand the units they are measured in
• To use the instruments to record the weather!
Weather is the day to day changes in the atmosphere.
temperature precipitation
wind speed
wind direction cloud cover
humidity
air pressure sunshine
What is the difference between weather and climate?p.7
Rain is a type of precipitation.
Precipitation is where water vapour in the air is cooled and condenses into water droplets.
Other types of precipitation are snow, sleet, hail, dew or fog.
How is rainfall measured?
rain gauge
Rainfall is measured with a rain gauge.
Rainfall 1.2 Instruments p.8
Thermometer
Temperature can be measured using a thermometer such as the liquid-in-glass type, where the liquid (mercury or spirit) in the bulb expands and rises up a capillary tube. Temperature is measured in either oCelsius or oFahrenheit.Temperatures are measured in the shade, so that the heat of the sun does not heat up the instrument being used.
How is temperature measured?
Temperature is how hot or cold it is.
Temperature p.8
anemometer
Wind speed is measured by an anemometer. This has metal cups which rotate in the wind. The stronger the wind, the faster the anemometer turns.
Wind is simply moving air.
Wind speed is how fast the air is moving.
How is wind speed measured?
Wind p.8
Wind direction is measured using a wind vane.
How is wind direction measured?
the arrow points into the wind
In this case, the wind has come from the north. It is a northerly wind.
See if you can spot a wind vane in your local area.
Wind direction p.8
It uses a scale from 0 to 12.
The Beaufort scale measures wind intensity using the effects of wind to estimate its speed.
Beaufort scale
0 on the scale means there is no wind.
How is wind speed estimated without an anemometer?
12 indicates hurricane conditions.
It is measured with a barometer (or a barograph).
Air pressure is the force exerted on the Earth by the weight of the air above.
How is air pressure measured?
Air pressure p.8
Weather instruments p.8
Which instrument? p.8
Rainfall is measured using a rain gauge.
Rainfall
Rain is a type of precipitation.
Precipitation occurs when water vapour in the air cools and condenses into water droplets.
Snow, sleet, hail, dew and fog are also types of precipitation.
Rainfall is usually measured in millimetres (mm).
How is rainfall measured?
• Your eyes are the most useful tools to measure the weather
• You can look at the sky and see how much is covered in cloud
• We record this in Oktas
• 1 Okta is ⅛th • A full sky of cloud
would be 8 Oktas
Cloud Cover
Cloud type
Weather Diary
• As a class you have to keep a weather diary for Canbury School
• In the garden a weather station has been set up
• Lets go outside and have a look
Pg 44
• Record what day you have to observe the weather at Canbury–Wednesday – EVERYONE– Thursday – – Friday – –Monday – – Tuesday –
• There is a clipboard in class to take out and then you must fill in the class diary
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