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How can we measure the weather? These icons indicate that teacher’s notes or useful web addresses are available in the Notes Page. This icon indicates the slide contains activities created in Flash. These activities are not editable. For more detailed instructions, see the Getting Started presentation. 1 of 28 © Boardworks Ltd 2005 Learning objectives Which instruments are used to measure the weather? How can you measure the weather? 2 of 28 © Boardworks Ltd 2005 Rainfall 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. Rainfall is measured with a rain gauge. rain gauge 3 of 28 © Boardworks Ltd 2005 Rainfall Rain facts! The greatest amount of rain recorded worldwide in 24 hours was in La Reunion in the Indian Ocean, when 1825mm fell between 7th and 8th January 1966. 4 of 28 © Boardworks Ltd 2005 Temperature Temperature is how hot or cold it is. How is temperature measured? 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. Thermometer 5 of 28 © Boardworks Ltd 2005 Temperature The highest temperature recorded in the UK was 38.5°C in Brogdale, near Faversham, Kent, on 10 August 2003. The lowest temperature recorded in the UK was -27°C at Braemar in the Grampians, on January 10 1982. 6 of 28 © Boardworks Ltd 2005 Wind Wind is simply moving air. Wind speed is how fast the air is moving. How is wind speed measured? 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. anemometer 7 of 28 © Boardworks Ltd 2005 Wind speed Wind facts! The strongest winds ever measured were gusts of 372 km/h (231 mph) at Mount Washington, New Hampshire, USA on 12 April 1934. 8 of 28 © Boardworks Ltd 2005 Beaufort scale The Beaufort Scale is a measure for the intensity of the wind based on conditions. It can be used to estimate wind speed. The Beaufort scale is divided into a series of values, from 0 for calm winds to 12 and above for hurricanes. 9 of 28 © Boardworks Ltd 2005 Wind direction How is wind direction measured? Wind direction is measured using a wind vane. In this case, the wind has come from the north. It is a northerly wind. the arrow points into the wind See if you can spot a wind vane in your local area. 10 of 28 © Boardworks Ltd 2005 Sunlight Sunlight is the amount of daylight. How is sunlight measured? The duration and the intensity of sunlight is measured using a Campbell-Stokes sunshine recorder. These focus light from the sun onto a piece of card where it leaves a burnt trace. The more sunshine there is, the longer the line. 11 of 28 © Boardworks Ltd 2005 Sunlight Sunlight facts! In December 1890, Westminster in London, there was no sunshine for the entire month. 12 of 28 © Boardworks Ltd 2005 Air pressure Air pressure is the force exerted on the Earth by the weight of the air above. How is air pressure measured? It is measured with a barometer. 13 of 28 © Boardworks Ltd 2005 Weather instruments 14 of 28 © Boardworks Ltd 2005 Cloud types There are four main cloud types: cirrus - the Latin for 'hair' for clouds that are wispy cumulus - the Latin for 'pile' for heaped looking clouds stratus - from stratum, the Latin word for 'layer‘, for sheets of cloud nimbus - the Latin word for 'cloud' for low, grey rain cloud How would you classify these clouds? cumulus cirrus nimbus 15 of 28 © Boardworks Ltd 2005 Cloud cover Cloud cover is the fraction of the sky covered in clouds. Cloud cover can be measured by observation. It is measured in oktas. clear sky 16 of 28 © Boardworks Ltd 2005 Which instrument? 17 of 28 © Boardworks Ltd 2005