Measuring weather: instruments and units

A fieldwork weather survey, step by step

Step through the survey in order. At each stage, ask yourself: what could spoil this reading?

1. 1Air temperature: probe clearHold the digital thermometer so the probe doesn't touch anything. Then read the air temperature off the screen.+
2. 2Write it in °C, to one decimal pointAir temperature is measured in degrees Celsius (°C). A good digital thermometer gives the reading to one decimal point, so write it that way, like 14.6 °C.
3. 3Wind speed: anemometer up highHold the anemometer high above your head, then read the wind speed off the screen.+
4. 4Wind speed in m/s, to one decimal placeWind speed is measured in metres per second (m/s), to one decimal place. Some anemometers allow other units, so make sure the whole class uses units that match.
5. 5Three readings, then the averageWind speed keeps changing, so don't trust one reading. Repeat it to get three readings, then find the average of the three.+
6. 6Record it: label + unitWrite every measurement down labelled, with its unit: °C for air temperature, m/s for wind speed, and mm for precipitation.

Spot the problem before you read on

Two pupils are out on the school field. Both of their readings will be wrong.

Ava has wrapped her whole hand round the thermometer probe "to keep it steady". Ben is holding the anemometer in front of his chest. Which fix sorts out BOTH of them?

Geography · Weather

Which part of the weather?

Which weather element does each one belong to?

9 of 9 still to sort.

Weather is the day-to-day condition of the atmosphere: temperature, sunshine, wind, humidity and precipitation. Sort each unit, instrument and form of precipitation under the element it goes with.

What you need to know

• Weather is the day-to-day condition of the atmosphere: temperature, sunshine, wind, humidity and precipitation.
• Precipitation is water falling from the sky as rain, snow, hail or sleet. It is measured in millimetres.
• Have a goYour friend Kai says, "Hail, sleet and sunshine are all precipitation, easy." One of those three is not. Which, and why?

  Sunshine. It's a different weather element, not water falling from the sky.

  Precipitation is water that falls from the sky as rain, snow, hail or sleet; sunshine is a separate element of weather.

• Air temperature is measured with a digital thermometer, held so the probe touches nothing and air can circulate around it.
• Read the temperature off the screen. It's in degrees Celsius, and a good digital thermometer gives it to one decimal point.
• Have a goFinish the sentence: air temperature is read off the screen in ______, and a good digital thermometer gives it to ______ decimal point(s).

  Degrees Celsius; one.

  Degrees Celsius is the unit for air temperature, and a good digital thermometer reads to one decimal point, so 14.6 not 15.

• An anemometer measures wind speed. Hold it high above your head so you don't hinder the reading and wind moves freely round the fan.
• Anemometer readings are in metres per second, to one decimal place. If it offers other units, a class should use matching ones.
• Because wind speed keeps changing, geographers take three readings and then find an average.
• Have a goZoe takes ONE anemometer reading, announces "Done!" and heads for the minibus. What should she do before she leaves, and why?

  Take two more readings, then find the average of the three.

  Wind speed keeps changing, so one reading is not enough; geographers take three and find an average.

• Label every recorded measurement and include its unit: °C for air temperature, m/s for wind speed, mm for precipitation.
• Windy areas may feel colder on our bodies, but geographers measure air temperature, which is unlikely to be affected by wind speed.

The big picture

In fieldwork you measure air temperature with a digital thermometer and wind speed with an anemometer, and you hold each one so nothing interferes with the reading. Wind speed keeps changing, so you take three readings and find the average. Every recorded measurement is labelled and has its unit: degrees Celsius, metres per second, or millimetres for precipitation.

⚠ Watch out

Writing down just the number. A bare 2.8 could be a temperature, a wind speed or a rainfall. Every recorded measurement needs a label and its unit, so it reads 'Wind speed: 2.8 m/s'.

Memory hook

Clear probe, high fan, three goes, unit on show.

Check yourself

Without looking back: list the steps for getting a wind speed in fieldwork, from picking up the anemometer to writing it down. Then compare your list with the process at the top.