Weather and Climate Lesson 2How 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!
p.7 What is the difference between weather and climate? Weather is the day to day changes in the atmosphere. temperature precipitation wind speed humidity wind direction cloud cover air pressure sunshine
Rainfall p.8Rain is a type of precipitation.Precipitation is where water vapour in the air is cooled and condenses into waterdroplets.Other types of precipitation are snow, sleet, hail, dew or fog.How is rainfall measured?Rainfall is measured with a rain gauge. rain gauge
Temperature p.8Temperature is how hot or cold it is.How is temperature measured?Temperature can be measured using a thermometer such asthe 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 ofthe sun does not heat up the instrument being used. Thermometer
Wind p.8Wind 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. Thishas metal cups which rotate in the wind.The stronger the wind, the faster the anemometerturns. anemometer
Wind direction p.8 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.
Beaufort scale How is wind speed estimated without an anemometer? The Beaufort scale measures wind intensity using the effects of wind to estimate its speed. It uses a scale from 0 to 12. 0 on the scale means there is no wind. 12 indicates hurricane conditions.
Air pressure p.8 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 (or a barograph).
Rainfall Rain is a type of precipitation. Precipitation occurs when water vapour in the air cools and condenses into water droplets. How is rainfall measured? Rainfall is measured using a rain gauge. Rainfall is usually measured in millimetres (mm). Snow, sleet, hail, dew and fog are also types of precipitation.
Cloud Cover• 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
• 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